A type of Texas Hold 'Em player. The All-In Hero has no actual skill in the game of poker, and the only way he can win is by constantly going "All-In" (betting all his chips in one bet) before the flop.
Most all-in heroes are the biggest suckers at the table, and even a player of moderate skill will bankrupt and All-In Hero eventually.
"I bankrupted that All-In Hero when I called his stupid bet with my with pocket bullets."
"What'd he have?"
"Fucking dumbass, gotta love All-In Heroes."