Android 20
Jinzouningen Nijuu Gou "Artificial Human Number 20"- In the manga, the real Dr. Gero is never actually seen, and in the anime, we only see him in brief flashbacks. The real Dr. Gero was a scientist for the Red Ribbon Army and was its only known surviving member after Gokou eliminated it. He invented 20 Android bodies in his life-time and began work on one ultimate biological warrior known as Cell. Most of his Androids were failures and were never shown. He invented the Androids primarily to kill Gokou, but Trunks infers that his larger scheme is something much larger than world domination. Keep in mind, in Trunks' future, Androids 19 and 20 did not exist, and Number 16 was either destroyed by Gero or never completed. Before creating Number 20, he created Number 19 to transplant Dr. Gero's brain into Android 20, which was built to look exactly like Gero's human body. After his brain had been moved into Number 20, Gero was able to continue his research and live on without fearing death due to old age. Number 20 is a particularly vicious villain. In the manga he squeezes off a human's head like a blemish. He's not much of a match for the likes of Piccolo, Gokou or Vegita even after absorbing energy. His only advantage is that he is an Energy Absorption Type Android who can absorb any ki attacks with a red ball in the palms of his hands, but Piccolo rectifies that problem simply by slicing of Number 2's right hand. Number 20 is killed by his own creation Androids 17. Number 17 slams his fist through 20's chest, kicks off his head, and then smashes his head under-foot.