Demon Clans (魔族 Mazoku)—alternatively referred to as Evil Tribes—refer to several groups of evil aliens that appear in the Dragon Ball series. To be a Demon Clansman you must be pure evil, and Demon Clansmen possess certain properties that their race does not normally have—notably King Piccolo and his offspring possessed abilities that other Namekians did not, such as the ability to completely destroy a Flying Nimbus and stop people's spirits from going to Otherworld by forcing them to remain dwelling in the living realm. King Piccolo was also able to birth mutant offspring, and Lord Slug and his clan were shown to have developed a weakness to sunlight. However, if someone loses their pure evil attribute, they will cease to be a Demon Clansman, as displayed by Piccolo—who loses his Demon Clan status by the time of the battle with Raditz.
The Demon Clan is one of the three different sub-groups a Namekian can end up as part of alongside the Dragon Clan and the Warrior caste, though the Demon Clan is unnatural compared to the other two. This clan uses kanji 魔 (Demon/Devil) as its symbol which is worn by King Piccolo and his son Piccolo (as a child) on their clothing. Tambourine also left behind a paper with the symbol on it when he killed martial artists such as Krillin as a calling card announcing their clan's return which is what allowed Master Roshi to realize that King Piccolo had been freed.
The only Demon Clan that appears in the original manga is King Piccolo's group, composed of King Piccolo and his offspring Piano, Tambourine, Cymbal, and Drum. King Piccolo's reincarnation Piccolo was also a Demon Clansman until the Raditz Saga. Despite not being a Demon Clansmen, Piccolo still clung onto his demonic heritage even adding his clan's symbol to the back of Gohan's Turtle Hermit to symbolize that Gohan was a student of the Demon Clan as he trained Gohan mainly because he had a premonition of his death which Kami felt was an attempt to leave behind some sort of legacy even if it was in the son of an enemy, though Piccolo himself ended up befriending the boy selflessly sacrificing himself to save his student's life. By the time of the Battle on Planet Namek, Piccolo had completely rejected his evil ways to the point Nail was willing to fuse with him (as Namekians can sense evil in a person's ki). However in the Garlic Jr. Saga it was suggested that his former Demon Clan status made him immune to the effects of the Black Water Mist as he was unaffected even after being bitten though used it to his advantage by pretending to have become infected and then pretending to infect Krillin who played along so they could free Kami and Mr. Popo. Despite no longer being a Demon Clansman and having turned his back on the evil ways of his clan, in the Dragon Ball Super manga during the Universe 6 Saga when Champa questions if Piccolo was really a Namekian, Piccolo boldy declares he is the reincarnation of the Demon King Piccolo indicating he is not ashamed of his demonic origins or status as King Piccolo's reincarnation.
Garlic and his son Garlic Jr., introduced in Dragon Ball Z: Dead Zone, are also Demon Clan leaders. Contrary to King Piccolo's Demon Clan composed of Namekians, Garlic and his son are from the Makyo Star (Makyo means "Demon-Evil" in Japanese, which is the "Realm of Demons" in Japanese Buddhism). Garlic assembled a demon army after being outclassed by the Nameless Namekian as successor for the then-current Guardian of Earth. An enraged Garlic led an attack on The Lookout in an attempt to take the position by force. The aging Guardian, however, managed to seal Garlic and the majority of his followers. To avenge his father, Garlic Jr. and his demonic followers (Ginger, Nicky, and Sansho) attack and try to kill the Nameless Namekian counterparts (Piccolo and Kami) whom Garlic Jr. blames for his father's demise. Years later, Garlic Jr. forms another Demon Clan with the Spice Boys (Spice, Vinegar, Mustard, and Salt), and uses Black Water Mist to turn earthlings who breath in it into evil "demons/vampires" who worship him and the Spice Boys.
Chi-Chi, Bulma, Master Roshi, and Yamcha were among the Earthlings effected which caused the dark impluses they would normally suppress such as greed to take over them to the point they'd be willing to kill for it. Even the relatively pure hearted can be effected as Chi-Chi became ruthlessly violent towards her son Gohan after being infected by the mist. However, compared to infected Bulma who became feral the infected Chi-Chi while ruthless was more far more controlled fighting in a cold hearted almost robotic manner. These differences are likely due to Bulma being impure of heart while Chi-Chi is known to be pure hearted as Bulma presumably has more negative and evil traits for the mist to draw out than Chi-Chi. The Black Water Mist is also capable of turning people infected into Demon Clansmen, they gain several new traits in this state, including red pupils, a feral nature, and the power to turn others into Demon Clansmen via biting. However, Piccolo is shown to possess an immunity to this as he only pretends to be infected, indicating that former Demon Clansmen may possess an immunity or resistance to the Black Water Mist's effects due to having once been Demon Clansmen.
Another Demon Clan led by a Namekian, Lord Slug, is featured in Dragon Ball Z: Lord Slug. Unlike the other Namekian Demon Clans which were comprised purely out of evil Namekians, Lord Slug's Demon Clan consists of several different alien races, including the Slug Soldier race, Medas, and a few other unnamed races, all possibly originating from Planet Slug. They have both a hatred and a weakness to sunlight, like Lucifer and his demons. Wings recognized Piccolo as a Demon Clansmen (unaware of his turn to the side of good) and suggested Piccolo join them, even believing that Piccolo reaching out his hand to him was Piccolo's way of accepting the offer, though Piccolo ended up using the opportunity to blast Wings in the face with an energy wave killing him.
Video Game Appearances
In Dragon Ball Z: The Legacy of Goku II, some of the Earth's animals remained infected by the Black Water Mist permanently after Garlic Junior's defeat due to the scared water not reaching certain areas. As a result, Gohan and his friends are left with little option but to kill them as they have been infected too long though fighting these infected animals serves as a form of training.
In Dragon Ball Online, King Piccolo's clan is revived in the form of a group of Dark Namekians, led by the Black Namekian Naraka. The Dark Namekians came about as a result of some Namekian refugees who fled to Earth following New Namek's destruction by Mira, who ended up settling next to King Piccolo's old throne which caused them to become tainted with evil over time. The evil in their hearts gave birth to the Evil Egg which contained Naraka. Meanwhile, Piccolo had discovered that some of King Piccolo's mutated offspring had survived the King Piccolo wars and had breed in the wild taking refuge in places such as under Pilaf's Castle. Piccolo knew he couldn't deal with them on his own though at the suggestion of Moori, he and the Namekians living on Earth captured them. Eventually Dragon Clansmen studied these demonic mutants which resulted in the development of the Poko Priest sub-class who could summon these mutant Namekians to aid them in battle by both good and evil Poko Priests. The Dark Namekians also created their own evil Eternal Dragon called Mr. Poko Poko who resembles an evil version of Porunga wearing clothes like Mr. Popo. The Dark Namekians attempted to take over the Earth at one point and also summon demonic mutated Namekianss to do their bidding. Piccolo became aware of the Dark Namekians and monitored their activities before finally calling in the Time Patrol in Age 1000, to put an end to their evil plans. Despite Time Breakers role in destroying New Namek, the Dark Namekians become allied with the Time Breakers with one of the Dark Namekian Elders even becoming a Time Breaker himself, even killing Naraka in cold blood after one if his subordinates was defeated by the Time Patrol. Ultimately this elder and the rest of the Dark Namekians were defeated by the Time Patrol in Age 1000.
In the Xenoverse series, the Majin race are considered Demon Clansmen as the Majin Kamehameha is referred to as a Kamehameha used by those of the Demon Clan as it can only be used by Majin. Mira can also use the technique, though it is unclear if this is due to Towa incorporating Majin DNA into him or due to him being Demon Realm race Bio-Android hybrid. Though the Demon Realm race are considered demons it in unknown if they can be considered Demon Clansmen or form Demon Clans themselves. Lord Slug even wonders if the Namekian Future Warrior is part Majin after noting how well Namekians and Majin fight together.
In Dragon Ball Xenoverse, a history change creates a alternate timeline where King Piccolo fuses with Kami and becomes a Super Namekian who gives birth to an army of mutant Namekian Demon Clansmen who are strong enough to combat Red Ribbon Androids and Babidi's Forces in a three way war, though they are all eventually defeated by the Time Patroller Percel.
In Dragon Ball Fusions, the Namekian Ryuto became a Demon Clansmen due to spending time in the Demon Realm. The Namekians living in the Timespace Rift have heard of Demon King Piccolo and his Demon Clan. This causes problems for Grand Elder Guru when one of his young children Moolin begins emulating King Piccolo by calling himself Demon King Moolin and getting into childish mischief such as insulting people and playing pranks. Guru tries to enlist Tekka's Team to talk some sense into him, but Kid Goku (who comes from the period when he was training under Kami) fears that Moolin had become Demon Clansman and jumps to the wrong conclusions. After Tekka's Team realizes Goku's fears were unfounded, Goten convinces Moolin to emulate the reformed Piccolo instead of his father. They later encounter King Piccolo himself who has been causing trouble for King Yemma in the Other World section of the Timespace Rift. King Piccolo battles Tekka's Team in his Great Namek form eager to take revenge on Kid Goku though he is defeated. King Piccolo can perform EX-Fusion with Dabura to create Demon King Daccolo, a Namekian Demon Clansman and Demon Realm race hybrid who possesses King Piccolo's Demon symbol tattooed on his chest and Dabura's Majin mark on his forehead.
In Dragon Ball Xenoverse 2, while training the Namekian Future Warrior, Lord Slug implies that Namekians can become corrupted by evil and turn into Demon Clansmen which may explain Lord Slug's evil nature as he was presumably corrupted by his Super Namekian power, though Lord Slug himself refutes this notion as he claims to have been nothing but pure evil since he was born and has never had a just thought in his life, considering himself evil incarnate and referring to himself as the "Nefarious Super Namekian". However Lord Slug does note they are not pure evil like himself, though after they complete his lessons he is hopeful that the seeds of a powerful dark force were planted in them. However he does note that one can utilize demonic techniques without the power of demons tearing them to shreds if they possess a strong enough constitution and it is implied the Namekian Future Warrior retains their pure heart despite his training. However as long as they serve him Lord Slug is willing to over look the fact that they are not a Demon Clansmen due finding their potential intriguing and due to his belief they may become a proper demon clansmen if they remain with his army. Additionally when he first starts to train them, Lord Slug is pleased to learn Warrior-types still exist among his weaker Namekian kin and decides he should one day invade Namek in order to build an empire of Namekian Demon Clansmen as well as claim the Namekian Dragon Balls for himself and his army. Demon Clan Namekians seem to be immune to negatively being effected by sunlight as Lord Slug is able to fight on helmetless Namek despite its three suns. Presumably this is due to their philology being adapted to a world with three suns thus they are not effected negatively by it as some weaker demons are though Lord Slug still Terra-Freezes worlds as his men are non-Namekian.
Lord Slug's clan are confirmed by both Slug himself and Old Kai to be an army of demons lead by Slug. Though Lord Slug is shown to be aware of his Namekian heritage, he still considers himself to be a demon and is pleased to have other demons join his ranks such as legendary Majin, however presumably this is because Slug considers himself a Demon Clansmen due to his pure evil nature as he is a Namekian who embraces darkness like King Piccolo and the Dark Namekians. According to both Chronoa and Lord Slug himself, Slug was Super Namekian born pure evil indicating has been a Super Namekian Demon Clansmen since birth. Lord Slug himself even states he has never had a just thought in his life and is evil incarnate, referring to himself as the Nefarious Super Namekian. However unlike King Piccolo, he never created any mutated offspring and instead founded an non-Namekian Demon Clan, though upon learning of the Namekian Future Warrior is a warrior despite their weak Namekian body, he resolves to return to Namek one day and create an empire made of demonic Namekians indicating he hopes to create his own Namekian Demon Clan one day.
Lord Slug explains that demons thrive in darkness and weaker ones are not strong enough to survive in it, though Lord Slug himself is unaffected presumably due to his Namekian physiology as Namekians developed on a planet with three suns and Lord Slug is to endure sunlight on Namek, Earth, and Conton City, though he still Terra-Freezes planets presumably to create worlds for his weaker demonic minions to inhabit as they travel the cosmos. It is implied that while demons live under a philosophy of survival of the fittest, though despite this their hatred of the light means they tend to not discriminate against demons who cannot survive in it as even the pure evil Slug notes is almost enough to bring sympathy to his cold, dead heart. Lord Slug also claims his techniques are demonic in nature and can only be mastered by those with some evil in their heart or inherently demonic like the Majin. After the warrior completes his training he assume the seeds of a powerful dark force were planted after all within them after all or at least they have a strong enough constitution to prevent the power of demons from tearing them apart indicating that demonic techniques of the Demon Clan can be dangerous otherwise. It is likely that the warrior remains uncorrupted as the Earthling Future Warrior can still use Power Pole Pro even after completing Lord Slug's training. Lord Slug implies that Saiyans, Earthlings, and Frieza Race can utilize demonic techniques if they become evil or have strong enough constitutions, despite not being demons as well. He also notes that Majin possess a natural affinity towards the power of darkness even if they are not inherently evil which is apparently a requirement for them to be fully considered to be demonic.