#4 Brock Lesnar
Brock Lesnar has quit WWE, or at least stayed away from the business, for long periods of time. Lesnar first quit WWE in 2004, at his prime, in the aforementioned match against Goldberg at WrestleMania 20 in 2004.
He made the decision to leave WWE at the age of 27 to try his hand at football, before wrestling in Japan and then MMA. He returned to the WWE 8 years later, and has featured sporadically in the WWE.
After quitting WWE, Lesnar spoke about how he is serious about a football career: "This is no load of bull; it's no WWE stunt. I am dead serious about this. I ain't afraid of anything and I ain't afraid of anybody. I've been an underdog in athletics since I was five. I got zero college offers for wrestling. Now people say I can't play football, that it's a joke. I say I can," said Lesnar back in 2004.