I saw someone make a similar list, though I'm not sure I quite agree with putting Dodoria and Yamu above Zarbon and Spopovich. So I made my own list, though the top of both our lists is the same. I also include unnamed characters who stand out enough, one of which has the second highest spot. This will mainly going by the original uncut DBZ, but will make reference to edited versions and Kai. Will keep it limited to the DBZ show and not include movies or anything that doesn't have Z in its title.
Offscreen[]
80: Pikkon, Olibu, Chapuchai, Migoren, Caterpy, Torbie, Frouq, Arqua, Maraikoh, Tapkar, Mushroom Announcer, and Papoi
They are already dead and spending their afterlife on Grand Kai's planet in Other World when we first see them. Their deaths are never seen and the cause is never revealed.
79: Bibidi
He is mentioned to be killed by Supreme Kai. We do see him in flashbacks but we never see his death scene.
78: Androids 17 and 18 (Cell's future)
They are seen only in Cell's flashback to when they kill Dr. Gero. Cell mentions that Trunks of his timeline destroyed them, prompting Cell to kill Trunks and use his time machine to go to the main timeline.
Nature[]
77: Guru (second time)
He dies peacefully of old age, and goes out with a smile.
76: Old Kai
He gives his life to Goku to revive him. The process seems painless and he immediately gets back up, as being in Other World, his death does little more to him than put a halo over his head, so it's easy to overlook.
75: Guru (first time)
He dies of a broken heart due to his sons being killed by Frieza. This is a lot more miserable for him than the second time, including the last time we see him alive before this.
74: Garlic
Many years prior to the events of the series, he is sealed in darkness by Kami, where, not being immortal like his son, he eventually died, presumably of starvation.
73: Tien Shinhan
He uses up all his energy for a Tri Beam in a vain attempt to kill Nappa. What puts him up the highest in this section is, it seemed a more painful death than the others and his hand was cut off moments earlier.
Physical attacks[]
72: Captain Strong
He is killed by Captain Ginyu with a punch simply for being a captain (besides Ginyu) that is trying out for the Ginyu Force. He seems to survive for a brief moment after this, but it's played somewhat comical.
71: King Vegeta
He is killed by Frieza with an uppercut.
Hit by an energy wave[]
70: North Supreme Kai
Majin Buu (in the form of Kid Buu) blasts him with an energy ball, which kills him. That's about it.
69: Orlen
Frieza kills him with an eye laser.
68: Appule
When Vegeta breaks out of the rejuvenation tank, the flash of light implies he used an energy wave, which seems to have hit Appule, as the next time we see him, he's laying dead.
67: Piccolo
He jumps in front of Gohan to protect him from Nappa's energy wave and is killed. In the uncut there is some blood, and Piccolo survives for a few moments before death, this likely being painful.
66: Cargo
Dodoria kills him with a breath blast. It's not very graphic or painful but he is a small child. In the Ocean dub this was censored, even making it sound like he escaped.
65: Dende
Frieza kills him with a finger beam, exploding on contact. Again, there's no blood and it seems to be instant, but he wasn't much older than Cargo and we got to know him for longer, and how he became friends with Gohan and Krillin and healed them during the fight with Frieza. (And unlike Cargo, not only is it not censored in the edited version, but in original series the episode is named Dende's Demise.)
Explosion[]
64: Frieza's minions on Planet Frieza
They are killed when Goku's power level overloads Planet Frieza's computer, causing it to explode. This includes the commander of Cui's race, the purple-haired minion, and possibly Malaka (though either he or someone identical to him is shown on King Cold's ship; in which case, he was killed in a similar explosion when Trunks blew up King Cold's ship).
63: Yamcha
A Saibaman jumps on Yamcha and selfdestructs. In original dub he is vaporized, but in uncut, his body remains intact, though he was killed instantly.
62: Chiaotzu
He selfdestructs in an attempt to kill Nappa, obliterating his body completely. What puts him above Yamcha is Nappa smashing him against rock walls repeatedly before the explosion.
61: Cui
Vegeta punches him into the air and explodes him with an attack that is dubbed "Dirty Fireworks". It's not overly graphic but more so than Chiaotzu's death.
60: Vegeta (second time)
He blows himself up in an attempt to kill Majin Buu. The sequence is more drawn-out than Chiaotzu, and after the blast, his body is turned to stone, and he falls and shatters to pieces like the Storm King. The pieces disintegrate to dust and blow away.
59: Krillin
Frieza lifts him into the air with his telekinesis, and when he makes a crushing motion with his hand, Krillin explodes. This is at the top of the exploding section because it seemed pretty painful, as well as triggering Goku's Super Saiyan transformation.
Aside from the next two sections, there are three more exploding deaths that will be listed higher up due to how gruesome they are.
Planet explosion[]
Usually these deaths are not explicitly shown, but then a whole planet is destroyed.
58: Atla and Lemlia
Their heartwarming reunion is cut short when Vegeta blows up Arlia. We don't see them during the blast, just a few moments before they are even aware that their "saviors" betrayed them.
57: Bardock
Along with most of the other Saiyans, he is blown up along with Planet Vegeta by Frieza's Supernova attack – though the attack hits him directly first.
56: Goku, King Kai, Bubbles, and Gregory
Goku teleports the selfdestructing Cell to King Kai's planet to save the earth. Cell explodes, destroying King Kai's planet, and Goku, King Kai, Bubbles, and Gregory along with it.
55: Gohan, Goten, Trunks, Piccolo, Tien Shinhan, Chiaotzu, Korin, Yajirobe, Captain Ginyu, Android 17, Android 8, and Turtle
They are all killed when Kid Buu blows up the earth, though only Gohan, Goten, Trunks, and Piccolo (who are unconscious) are shown during this scene. This could also include Icarus and Chobi if dragons and dinosaurs were excluded from the Human Extinction Attack. What puts this at the top of this section is, well, Earth is blown up.
Blown up by an energy wave[]
They get blasted and then explode, with nothing left of them except maybe dust.
54: Android 17 (Trunks's future)
Trunks kicks him to the ground and blasts him with an energy wave, and he explodes.
53: Yamu
Horrified at Spopovich's death, he tries to fly away, but Pui Pui shoots him with an energy ball, and he explodes.
52: Spice and Vinegar
After Vinegar sends Krillin falling, and he and Spice stop Gohan from saving him, Gohan gets enraged and blasts Spice and Vinegar at the same time. This is a little more drawn-out than Yamu, as they have time to react in shock and horror before Gohan's Masenkos blow them both up.
51: Paperclip Truck Driver
His truck is blasted by Vegeta (who was aiming for 18 but she dodged it) and blown up with him inside it. (Note that he survives in Kai)
50: Android 18 (Trunks's future)
Trunks blasts her in the face with an energy wave and she explodes.
49: Kibito
Similar to 18, Dabura blasts him in the face. This is extended a few seconds before Kibito explodes.
48: Android 19
Though he is a purely mechanical android, Vegeta pulls 19's hands off, and they gush red oil symbolizing blood. Conclusively proving to Vegeta that androids experience fear, 19 attempts to escape but Vegeta destroys him with a Big Bang Attack, causing a massive explosion and leaving only 19's head, which malfunctions and dies.
47: Recoome
After being knocked out by Goku with one blow, Vegeta blasts him with an energy wave and he explodes. (Though, in a blooper, original series shows his body still intact alongside Burter and Guldo's corpses when Gohan is flying back to the ship) What puts him above some of the others on this list is that he is unconscious and helpless, showcasing Vegeta's lack of mercy.
There is one more that would go here but I felt he had to go higher due to other factors, including gore.
Disintegrated[]
Some would put this a lot higher but it usually doesn't look that graphic. Taking that into account I do put it above the last section.
46: West Supreme Kai
After she is beat up by Majin Buu (in the form of Kid Buu), he destroys her with an energy wave to the back point blank. What puts her this low is we don’t see the actual disintegration, just a flash of light in the distance.
45: Pui Pui
Vegeta destroys him with an energy wave, point blank. This time it's from the front and is shown, but not really graphic.
44: Namole
Frieza destroys him with an energy wave, in the uncut for being cowardly, and in the Ocean dub, for second-guessing his decision. It's sudden and instant.
43: Van Zant
Evil Buu destroys him with an energy wave, also at close range. Like Pui Pui it's pretty quick and not very graphic, though Van Zant is clearly more terrified. (Of course, it's practically impossible to feel sorry for him)
42: Dodoria
After Vegeta goes back on their deal, a terrified Dodoria attempts to escape to Frieza but Vegeta disintegrates him with an energy wave. Though Dodoria is cross-eyed in the last second of his life, the death is pretty quick and not too graphic.
41: Cell (Trunks's future)
Trunks destroys him with an energy wave. It's a little slower than some of the others but not by a whole lot.
40: Nappa
Goku beats up Nappa, apparently breaking his back. Nappa asks Vegeta to help him up. Vegeta takes his hand, then throws him into the air and blasts him with an energy wave for losing to Goku. This is more painful and drawn-out than Dodoria even though it's not that graphic, as he is vaporized, and vanishes in a flash of light. There is an explosion but this seems to fit more in "disintegrated" first.
39: Tsuno
Vegeta disintegrates him with an energy wave. It's not much more graphic or slow than Dodoria but what puts him this high is that he is a non-villainous character who is directly murdered by Vegeta (who later becomes one of the Z Fighters) and is not revived, and also takes place directly after Vegeta slaughters the entire village (except one Namek who is killed by Orlen).
38: Yetti
He is blasted by Nappa with an energy wave, disintegrating him immediately. This would be near Pui Pui if not for the fact that Nappa pulls his finger off first, and I think there is some blood during this scene.
37: Salt and Mustard
In his rage at Krillin being beaten up by Mustard and nearly killed by Salt, Gohan blasts Salt with a Masenko, causing him intense pain for several seconds before he disintegrates. Mustard attempts his revenge but Gohan kicks him in the face and disintegrates him with another Masenko, slightly faster than Salt.
36: Kid Buu
Previously known as Evil Buu and Super Buu, Kid Buu is destroyed by Goku with a Spirit Bomb. The disintegration is a little slower, explicitly shown, and looks somewhat painful, but not that graphic.
35: Cell
During a long and intense beam struggle with Gohan, Cell nearly wins before Vegeta hits him with a Big Bang Attack, distracting him long enough for Gohan to overpower Cell and disintegrate him. This is the most drawn-out disintegration and probably the most painful; We see Cell's face distort, before he slowly disintegrates, down to his last cell, which is then destroyed.
There is one more disintegration death but it's so brutal I'm saving him for the top section.
Lack of air[]
34: Oggers, Strock, and Goose
Ginyu knocks Oggers into space for lacking the style to be on the Ginyu Force, and presumably does the same to Strock and Goose, though one could argue that he could have killed those two in a similar style to Captain Strong instead, but we see him knock three unnamed minions into space as well.
33: "Mean man"
A man that Majin Buu saves from drowning. When he notices that his savior is Buu, he starts screaming, to which Buu gets annoyed and blasts him into space, as he had intended to do to Gohan. "Buu make mean man gone!"
32: Bund and Vug
Gohan punches Vug, Krillin kicks Bund, they collide, and they fall into a lake and drown. (Note: Some have called them Banon and Sui?)
31: Trunks (Cell's future)
Cell strangles Trunks of his timeline with his tail. It's only briefly shown but is the most violent of this section.
Neck broken[]
30: Burter
After being knocked out by Goku, Vegeta stomps on his throat. We see a shot of his corpse with the big dent in his neck from where Vegeta hit him. He is unconscious, and doesn't feel a thing, but at the same time is completely helpless when Vegeta kills him.
29: Moori
Dodoria beats him up and then snaps his neck in a fairly realistic and violent way. This is censored in the Ocean dub where it is implied that Dodoria just beat him to death.
Projectile / Beam through the chest[]
28: Farmer
He attempts to shoot Raditz, who catches the bullet and flicks it back at him. I don't think anything was graphically shown but he effectively gets shot.
27: King Moai
Vegeta shoots a rock through his chest. This is more graphically shown than the farmer, but not really bloody.
26: Future Trunks
Cell shoots a Death Beam through his chest. We see a bit of blood, but not much.
25: Vegeta (first time)
Frieza, after giving him a brutal beating, shoots a Death Beam through his heart. In the uncut, he coughs up blood, putting him above his son (along with how badly injured he was before the deathblow). Plus, where Trunks was killed almost instantly, Vegeta still lives for a few moments, long enough to tell Goku his backstory while shedding tears over it, also making his death quite emotional.
24: Raditz and Goku
As Raditz holds Goku in place, Piccolo shoots a Special Beam Cannon, which tears through both their chests. This is higher than Vegeta and Trunks because the Special Beam Cannon is thicker and seems to be drilling through them, though Kai tones down the graphicness of the death, and the Ocean dub even more. Raditz dies before Goku as Piccolo finishes him off with an unspecified attack, but for both the mortal injury stands and Raditz has enough time for some final words.
23: Earth's population
Most of the humans on Earth not eaten by Majin Buu are killed by Super Buu's Human Extinction Attack, where he shoots energy waves through them.
Casualties here include Dr. Brief, Mrs. Brief, Pigaro, Maron, Mr. Shoe, General Tao, King, Mr. Lao, Lime, Mr. Bourbon, Bertwell and Kasdan, Vodka, Jimmy Firecracker, Lionel, Miss Pisa, Caroni, Piroshki, Erasa, Sharpner, Nerd, Mrs. Beakman, Angela, the Red Shark Gang, Mr. Musuka, Announcer, Egessa, Ekossa, Egessa's mother, Little James, Koryou, Mokki, Big Booger, Pintar, Jewel, Killa, Mighty Mask, Tommy (maybe), Pit Bull Pete and his partner, Wild Tiger, Knock, Narig, Captain Chicken, and Otokoski (though a few of them, like Mr. Bourbon and Vodka, are filler and are absent from Kai), also Bora, Upa, Nam, and Devilman, and any surviving characters from Dragonball who do not appear in DBZ. May include dinosaurs or dragons like Chobi and Icarus.
While less graphic than some of the others on this list, it's at the top of this section for the mass murder/near-genocide aspect of it.
There is one more "energy wave through the chest" but he'll go in a higher section due to being more graphic and gory.
Head destroyed[]
22: Dr. Gero (Cell's future)
17 cuts off his head, which is still alive, and then 18 destroys his head with an energy wave, obliterating it in a flash of light.
21: Dr. Gero
17 kicks off his head, which is still alive, then stomps on his head, crushing it.
20: Android 16
Cell destroys his body. His head survives, and, as he gives final words to Gohan, encouraging him to save the world, Cell stomps on his head, crushing it. This is shown in more detail than Dr. Gero, plus he was a lot less evil than him and presumably never gets revived. Nevertheless, as an android, he is lower on the list than the next three.
19: Esau/Lesoy
There is some debate as to his actual name (closed captoins of old Ocean episode said Lesoy, but another site I was at called him Esau) but Vegeta destroys his head with a finger beam.
18: Babidi
Majin Buu grabs him by the throat and punches off his head, with enough force that it looks like he blasted him with an energy wave.
17: Guldo
Vegeta decapitates him, to which he is still alive, and then destroys his head with an energy wave. The actual head destruction is less graphic than Babidi's but the decapitation puts it above him, and was censored in Ocean dub.
There is one more of these but it will be in the final section due to how gruesome it is.
Eaten[]
16: Blueberry and Raspberry
They are caught by the giant grab with her claws and dragged underwater, presumably to be eaten. If not, then she likely sliced them to pieces with her claws.
15: Gregor
After being stabbed by Esau/Lesoy, he is thrown into the Pit on King Moai's orders, where he is eaten by Yetti. This occurs offscreen, but the last we see of him is him backing away in terror and begging the monster not to eat him.
14: Dabura
Majin Buu turns him into a life-sized cookie and stuffs him into his mouth whole, before chewing and swallowing him.
13: Krillin, Android 18, Marron, Yamcha, Puar, Bulma, Videl, Master Roshi, Ox-King, Oolong, and Mr. Popo
They are turned into chocolate and eaten by Super Buu. Only Krillin is eaten onscreen, and Buu eats 18 and Marron before turning the others. While not as drawn-out as Dabura's death, what makes this more gruesome is a.) This is a mass murder of many Z Fighter allies, and b.) Marron is a small child who is absolutely terrified during Buu's speech on what to turn them into. In Other World, Krillin implies that they are alive and conscious as chocolate bars when he eats them.
12: Old man
A minor, unnamed character, but I have to put him at the top of the Eaten list because of just how messed up it is: Majin Buu, having become friends with Tommy, a blind boy whom he healed, turns the old man into milk and gives it to Tommy to drink. Though we don't see Tommy drink him onscreen, the fact that an innocent child unknowingly drinks another human is pretty disturbing.
Most brutal deaths[]
These are deaths that would shut up anyone who says DBZ is a "kid show".
11: Android 17
Depending on how you look at it, 17's first death could have either occurred when Cell selfdestructed (see Goku, King Kai, Bubbles, and Gregory), or, if he survived the selfdestruct on account of being part of Cell, when Gohan destroyed Cell with a Kamehameha (see Cell), as either way, he was inside him at the time. Given how 18 is unconscious when Cell throws her up, it can easily be assumed 17 was unconscious during his death, whichever point it was at. This is why he is the lowest in this section.
However, it was the moment leading to his death, which caused him to definitely be counted among Cell's victims on Earth, that earns him a spot in this section. Cell opens his tail up and puts it over 17's head, to which we hear his muffled screams and see him physically struggling to get free, before Cell slowly swallows him whole with his tail, to which Tien is absolutely horrified. This is the last thing 17 would be conscious of before dying, and the next thing he'd be aware of would be arrival in Other World, so for all he knew, being absorbed in itself killed him.
10: Chi-Chi
Super Buu turns her into an egg and stomps on her. The other list I saw put her at second highest.
9: Jeice
Vegeta kicks Jeice away, and then shatters his ribs with a karate chop. This is very painful for Jeice, who coughs up blood (and, in the TV airing of the episode, moans in agony for about ten seconds) before Vegeta puts his hand right in front of his face. In Kai, Jeice simply says "Please, spare me, I beg-" before being killed mid-sentence, while in the original series, he desperately yells "VEGETA! NO! NOOOOOOO!" Either way, Vegeta destroys him with an energy wave to the face, point blank.
8: King Cold
It's mainly the injuries leading to his death that put him this high, combining the "beam through the chest" and "blasted and explode". Trunks shoots an energy wave through King Cold's chest, blasting him into a rock wall. He survives, but there is blood all over the wall from where he hit it and slid down. King Cold then begs for his life, but Trunks, knowing he can’t be trusted, blasts him with another energy wave and he explodes.
7: Yakon
Yakon eats Goku's light energy from his Super Saiyan form. Goku maintains his Super Saiyan form as Yakon keeps eating his light energy against Babidi's orders. Soon Yakon eats too much, as he expands and explodes. While this looks painful, it's the lowest of the three of these deaths because the explosion is a standard one with no blood or guts, and Yakon could have stopped at any moment, his own gluttony did him in.
6: Spopovich
When Babidi decides Spopovich has outlived his usefulness, he casts a horrific spell on him. First, Spopovich's eyes bulge out and go cross-eyed, and then he starts to painfully expand while Yamu stands to the side trembling with fear. There is even a shot of blood gushing from Spopovich's nose before he explodes. Again, the explosion is standard, but he's above Yakon because his death looks more gruesome and painful. The sounds are pretty bone-chilling in the original uncut as well.
5: Zarbon
Vegeta slams his fist through Zarbon's stomach. We see Zarbon's blood pouring out, with Vegeta's fist still buried inside. This is very painful for Zarbon, who doesn't even seem able to move as a result, and then Vegeta blasts a massive energy wave through his chest, sending him flying. He lands in a pool of water, but it can be debated whether he actually drowns because, after that blast, he probably didn't even have lungs to breathe with. In the uncut he may already be dead before he hits the water, but in the Ocean dub (which censored the more graphic parts of it), he yells Vegeta's name before the splash, implying a slower death at the bottom of the water hazard.
4: Frieza
He gets chopped in half by Trunks with his sword, and we see an extended shot of him in two pieces while King Cold's face turns blue with horror. Trunks then slices Frieza into pieces, and then finally blasts him with an energy wave, reducing him to dust.
Despite Frieza being the most evil villain in the series and some of his horrific acts being clearer in original dub once FUNimation takes over, the edited version of the episode removes any shots of Frieza where he is in two or multiple pieces, not showing him again after the "splitscreen" until he is dust raining down. That's how graphic his death was.
3: Marvin
Disappointed that he was unable to give him Goten, Trunks, and Piccolo's locations, Babidi makes Marvin's head expand and explode with his magic. This is more graphic than Spopovich's death; though partially obscured behind some plants, it is a more bloody explosion.
2: Rich man
The first person to be absorbed onscreen by Cell, and thus the most drawn-out instance. Cell stabs the rich man in the back with his tail and absorbs him, starting by slowly sucking out his insides. We see his hand and face gruesomely shrivel up, while we hear him screaming in agonizing pain until the moment of death, and his skin is the last part of him to be absorbed.
Being quite young when I first saw this, this was one of the moments that weirded me out the most (definitely more so than Neflite's death in Sailor Moon), and the only part that was censored on TV was the shots of his face. This is made worse by how many other hundreds of people died this way, though apparently faster, even though they were all revived.
1: Smitty
Easily the most gruesome death in the series and the most graphic parts of it were censored on TV, and when my brother saw this he said it should be rated R. Smitty's death is kinda the opposite of the rich man, and the third and most gruesome "expand and explode" death (fourth if you count Marvin).
Super Buu turns into liquid form while stretching and forcibly goes down Smitty's throat. This is a lengthy sequence during which Smitty slowly starts to expand, more gruesomely than Spopovich or Yakon. All the while his eyes are bulging as he is unable to stop drinking Buu. As Buu finally finishes going down Smitty's throat, Smitty gets fatter and fatter until he explodes. There's no blood or guts shown, as the explosion consists entirely of the pink liquid that is Buu, but it's still incredibly graphic and gruesome.