Barry Greenstein (born December 30, 1954, in Chicago, Illinois) is an American professional poker player and former mathematics postgraduate student.

Greenstein donates part of his profit from tournament winnings to charities, primarily Children Incorporated, earning him the nickname "the Robin Hood of poker".

[2] After graduating from Bogan High School,[3] he earned a bachelor's degree in computer science from the University of Illinois at Urbana-Champaign.

[16] Tuan Le, a WPT Season 3 champion, claims that book showed him how to succeed on the poker circuit.

Greenstein is known for giving away a free copy of his book to the player who eliminates him in a tournament, including his autograph and details of the hand.

After winning $770,000 at Larry Flynt's $1 million Seven-Card Stud event in 2003,[21] he donated $440,000 to Children Incorporated – a gift of $1,000 to each of the charity's 440 employees.