Dude doesn't even know his own name anymore. Just accept it and fade away.
~ Zach telling Gumball to accept he will vanish
Forget it. I’m the boss of this game. I know all the combos.
~ Zach's last words to Gumball on changing his name through the game
Zach is the evil alter-ego of Gumball Watterson, and the main antagonist of The Amazing World of Gumball Season 3 episode, The Name.
When Gumball learns his real name is Zach, he develops an alter ego in which he perceives himself as a cool winner. Unfortunately, the alter ego is also a major jerk to everyone, especially his family, and nearly takes over Gumball and his memories, whom Zach sees as a loser. While the Wattersons were rushing to the City Hall in their car in order to change his name to Gumball legally, Zach attempts to erase Gumball from existing; like trying to shoot Tobias with a bazooka, and attacking Carlton and Troy with multiple tennis balls, and replacing them with fabricated memories as Zach. Inside his mind, Gumball struggles against Zach, but eventually triumphs and defeats Zach by seeing the memory when he actually won something. He types his name on the game, Zach then vanishes and Gumball wakes up before writing down his name at the town hall, and his family was happy to have him back.
He is the third non Fan Villain in the show that dies, first being Virus and the second being Ant-One.