His father, Isidore ('Ido') Ungar, was a bookmaker and loan shark who ran a bar/social club called Foxes Corner that doubled as a gambling establishment, exposing Stu to gambling at a young age. He was raised on Manhattan's Lower East Side. Ungar was born to Jewish parents Isidore (1907–1967) and Faye Ungar (1916–1979). Additionally, Ungar is one of only four players in poker history to win consecutive titles in the WSOP Main Event, along with Johnny Moss, Doyle Brunson and Johnny Chan. He is the only person to win Amarillo Slim's Super Bowl of Poker three times, the world's second most prestigious poker title of its time.
Ungar is one of two people in poker history to have won the World Series of Poker Main Event three times. Stuart Errol Ungar (Septem– November 22, 1998) was an American professional poker, blackjack, and gin rummy player, widely regarded to have been the greatest gin player of all time and one of the best Texas hold 'em players.
