#20, also known as Dr Gero, begins his career as a famous scientist working for the Red Ribbon Army. His brilliant invention skills leads him into developing artificial intelligent, hence moves on to creating androids. In the beginning, most of the androids he has created are failures and none of them are functioning properly. Eventually, when Gokou infiltrates the Red Ribbon Army, and Red Ribbon Army needs more soldiers, Dr Gero has no other choice and deploys his first android, Android #8. Dr Gero, sees little success with #8, has the evil thoughts in his mind that if he develops better androids, he might be able to use them not just to fight, but to conquer. Hence Dr Gero heads back to his lab, and starts to develop stronger androids. In a few years time, he has created #13, #14, #15, #16, #17, #18 and #19. Dr Gero, also turns himself into an android, by implement his brain into a custom made robot shell, and becomes Android #20. All the androids he has created have the same primary objective, either to kill Gokou, or to conquer the universe. However, the success does not last long for Dr Gero. Obviously Dr Gero does not aware that the androids might become rebellious, and his carelessness ultimately leads to his death, when #17 suddenly rebels and beheads him. After the death of Dr Gero, the main computer in his lab continues to function, and takes on Dr Gero's role to create even more powerful androids. Cell is later created by Dr Gero's computer.