Cell  The ultimate creation of Dr. Gero. After  extensive research of gathering information about the Namic,  Saiyajin and Freeza's race's fighting techniques as well as their  biological make-up, Dr. Gero was able to combine the best of  everyone into a single entity called Cell. Cell's purpose seemed to  be nothing but to do be ultimate fighting machine regardless of the  methods (such taking millions of lives to fuel his  power). Cell's power is not fully realized until he absorbs  both #17 and #18, which is called the "Complete Form" or the 3rd  stage of development. After he had reached Complete Form and  believed that no could defeat him, everything became a game to  him. He subsequently spared the life of Trunks after Trunks  forfeited the fight against him. He announced the Cell Game and gave  the Dragon Ball Warriors time to "get up to speed" in order to seek  more challenge. He had always believed that Son Goku was his  ultimate challenge. It wasn't until Son Goku forfeited the fight and  handed it over to his more powerful son, Gohan (no pun  intended). When Cell was finally confronted with defeat and  even death by Gohan, nothing was a game to him anymore. Vegence was  the only thing that filled his evil mind. He became much more  powerful after his unsuccessful attempt to destroy the world by his  self-destruct mechanism. But he was still no match for Son Gohan.