Android 9 is a fully artificial android model constructed by Dr. Gero.
Dragon Ball Z
Android 9 was an entirely mechanical Android constructed by Dr. Gero at some point following the Red Ribbon Army's defeat but possessed a problem and so was destroyed.
Other Dragon Ball stories
Dragon Ball SD
Dragon Ball Online
In Dragon Ball Online, Android 9 has been rebuilt and seemingly allied himself with the Red Pants Army, and is fought in the ruins of the Red Ribbon Army Headquarters located near Korin Tower. He is much larger than his template, to the extent of towering over the main character by a head's length, ironically fulfilling his template's wish to be taller in a sense. He also seems to be wearing some sort of ceremonial scarf adorned with Red Ribbon logos.
Android 9 is capable of taking on members of the Time Patrol, however, he is not as powerful as fellow Mechanical-type modelled after a human template Android 16 - who is the most powerful of the Red Ribbon Androids other than the Bio-Androids Cell and Android 21.