Small and unassuming, Barry Greenstein is not a man who intimidates or who inspires fear. But poker players beware: The Robin Hood of Poker doesn't steal money from the rich; he steals pots from the fish. And he's been doing it since childhood.

Born and raised in the Chicago suburb of Scottsdale, Ill., Barry learned to play cards at a young age from his parents. Gin rummy, hearts and poker were the games of choice, and Barry was particularly gifted in poker. His parents encouraged him to develop a calm and analytical game, and by the age of 12 he knew he could make a good living at the green felt. He started playing home games a year later, making the rounds and cashing up to $50 a night.

Despite his talents as a card shark, Barry wasn't sold on a career as a professional poker player just yet. He grew up in a happy home where a strong sense of integrity and making a difference were encouraged, and poker wasn't exactly known for its moral standards or positive influence on people's lives. Besides, Barry craved more intellectual stimulation than poker could give. This, after all, was a boy who created his own computer software when he was 15 and who harbored hopes of becoming a doctor and curing diseases.

A strong student in mathematics and computers, Barry kept up with his studies at Bogan High School during the day and built his bankroll at night. His routine didn't change much at the University of Illinois at Urbana-Champaign, where he earned a bachelor's degree in computer science in just three years, along with untold thousands in poker winnings.

Barry went straight from his undergraduate studies to a Ph.D. program in mathematics and spent the next 10 years earning his doctorate degree, playing poker and building his bankroll all the while. Shortly before completing his studies, Barry met and married his (now ex-) wife, Donna, who had three kids from a previous relationship. In order to gain full custody of the children, Barry was advised by their attorney to get a job that didn't involve gambling.

So, Barry gave up school and full-time poker and moved with his family to the Silicon Valley where he joined four others in a start-up company now known as Symantec. Barry quickly located a good cardroom and settled in to design pioneering software programs. He and Donna subsequently gained custody of the kids and had two more in 1987 and 1988.

Despite negotiating a clause in his contract allowing him to complete his Ph.D., Barry chose a different path. The company was too dependent on his skills to give him the time he needed for his doctorate, so he agreed to stay and help finish the software program, Q&A, he was working on instead.

In 1986, Q&A was named product of the year in almost every industry magazine, and to this day it remains one of Barry's proudest accomplishments. The success of Q&A put Symantec on the road to becoming one of the top computer software firms in the world, and taught Barry the maturity, discipline and patience he needed to see long-term projects through to the end - such as late nights at the poker table.

Throughout his years in California Barry had been playing No-Limit Hold'em at the Cameo Club in Palo Alto. The games boosted his paycheck and helped support his family and their lifestyle. But in the late '80s they began to serve a more serious purpose when Donna was diagnosed with multiple sclerosis, and their daughter Melissa began suffering from liver problems so severe they eventually necessitated a liver transplant.

Barry began to spend more and more time at the tables, returning to the poker-playing/work schedule of his early years, except with crazier hours. It lasted until 1990, when Barry quit Symantec. Unable to justify spending so much time away from the poker table when the money was so good, and in need of a job that allowed him the freedom to spend time with his family, the 36-year-old put away his software and took to the tables in earnest.

Bellying-up to the games at the Cameo Club 12 hours a day, most days of the week, Barry's bankroll grew fast, and so did his skills. Though side games were his bread-and-butter, in 1992 he decided to enter his first tournament: the $10,000 WSOP Main Event in Las Vegas.

Undaunted by a 36-player starting field packed with bona fide pros like Johnny Chan, Todd Brunson, Bobby Baldwin and Berry Johnston, Barry ploughed his way through and placed 22nd in the event for an $8,080 payday.

It was around this time he and Donna decided to get a divorce, and after a three-year battle Barry was awarded full custody of their children. During this difficult period Barry met Vietnamese player Mimi Tran and they cut their infamous deal: Barry offered to teach her poker in exchange for Vietnamese lessons, which he hoped would help him communicate with the many Vietnamese players he anted up against.

In the following years Barry kept up his No-Limit Hold'em game and began to play Limit Hold'em as well, ripping up the felt at ring games across California and Las Vegas and building a reputation as one of the top players in the world. He continued to enter and cash in tournaments through the '90s but his big break didn't come until 2003, when he won Larry Flynt's $1 million Seven-Card Stud event at the Hustler Casino.

It was after this tournament that he made his first major donation to his charity of choice, Children, Incorporated. He had been involved in the charity for some time, sponsoring several children in the United States through the organization and taking his kids to meet them. But with his Hustler win he decided it was time to make to take his philanthropy to the next level: He donated a large chunk of his $770,000 first-place win to the organization.

Since then he has cashed in dozens of tournaments and donated millions of dollars to a myriad of charities, including Children, Incorporated and Guyana Watch, the favored charity of fellow pro Victor Ramdin. But as the years passed and poker grew, Barry realized a change was needed if he was to keep himself afloat financially and continue to donate his winnings. So, he devised a more sustainable solution.

"I will be donating my net earnings from tournaments at the end of each year," Barry told PokerListings.com in 2006. "Until now, I was donating the pay-off each time I cashed but I can't afford to continue doing that. I didn't anticipate the growth and expense of tournament poker."

And grown it has. Since Barry first entered the Cameo Club, the number of ring games and tournaments on the West Coast has grown exponentially - and Barry's cashes along with them.

Over the years he has placed in more than 30 WSOP and 15 WPT events. He is a regular player in the highest-stakes cash games in Vegas and California, including the Big Game at the Bellagio, and has appeared in several major televised poker tournaments and TV shows, such as High Stakes Poker, the NBC Heads-Up Championship and Poker Superstars Invitational.

He has also made a name for himself as a poker author. After much haranguing, he was persuaded to write a chapter for Super/System 2, the highly anticipated sequel to Doyle Brunson's poker how-to book, Super/System. Barry found the experience so enjoyable he ended up writing his own poker tome, Ace on the River, which is more about the lifestyle of a poker professional than poker strategy.

When not at the poker table, Barry spends as much time as possible with his children. He plays golf and bridge, goes for dinners and watches movies, and generally enjoys his house and family in California. He spends time fulfilling his duties as a member of Team PokerStars, playing tournaments and consulting in the design of the room's software, and also works with his poker pro son, Joe Sebok, on poker-related projects.

Barry's game is still one of the best in the world. And despite 15 tournament cashes in 2007, including a seventh-place finish in the WSOP H.O.R.S.E. event, and nonstop ring-game action, he is convinced that a professional poker player's game will inevitably deteriorate with age. Humble about his talents, honest about his weaknesses, he may yet prove himself wrong. And if he does, he'll be the first to admit it.