Micky Rosa is the hidden main antagonist of the 2008 heist movie, 21. He was played by Kevin Spacey.
The evil MIT professor tests Ben with the Monty Hall problem and Ben solves it. When he looks at Ben's non-linear equations score which is 97% and this leads to Ben joining Rosa's blackjack team. The team consists of card counting and is divided in 2 groups. Ben says he only agrees to participate so he can pay for med school.
The team go to Las Vegas and through innumerable weekends, Ben finds that he enjoys the high dollar life of being a big player. Rosa later cuts Fisher, member apart of his team and fool, after Fisher insults Ben and does a melee, in which Rosa and the team race to cash in their chips before the casino swaps out, a practice after a fight. In the meantime, security chief Cole watches the blackjack team of Rosa and Ben gets sidetracked by blackjack and does not complete his part of an engineering competition, which he loses his pre-blackjack friends. Ben's next trip to Las Vegas turns into a disaster when he loses $200,000.00 and Rosa furiously leaves the team and says to Ben he'll pay him back sooner or later.
Then Rosa betrays Ben by informing Williams of him and Williams beats Ben up and then frees him with a deadly warning. When Ben returns to MIT, he learns that he's been given an incomplete grade, in a class, which hurts his graduation, and all his winnings and money have been stolen from his room. He knows Rosa is behind all this but can't prove it and makes amends with his blackjack friends and then makes a deal with Rosa of returning to Las Vegas for one last attempt before the casinos put in biometric software, that will hunt card counters down if Rosa, who was a great big player, also plays with them.
All in agreement, they return to Las Vegas winning $640,000.00 before leaving with their chips from Williams and his men on to them. Ben and Rosa split up, with Rosa getting the bag of chips, and escaping in a cab. Rosa plans to steal the money but discovers the bag is full of chocolate candy chips and the casino manager is driving him. It turns out that Ben and Williams made a deal that Williams would allow Ben to return for 1 night and win a lot of money, in exchange for Rosa, because when Rosa and Williams were younger, Rosa won a 7 figure sum at William's casino by counting cards, in which Williams lost a pit boss job. Later Williams confronts the captured Rosa and it's unknown what happens to Rosa.
- Rosa was presented as the good guy and Williams appeared to be the villain, but it turned out to be the other way around.