Sam "Ace" Rothstein is a fictional character from the 1995 film Casino, directed by Martin Scorsese. He is portrayed by actor Robert De Niro and is based on the real-life figure Frank "Lefty" Rosenthal. Ace is a skilled sports handicapper and casino manager in Las Vegas during the 1970s and 1980s, known for his sharp business acumen and ability to manipulate the gambling system. In the film, Ace's rise to power is marked by his partnership with the Chicago Outfit, a powerful crime syndicate. His story explores themes of greed, betrayal, and the dark side of the casino industry, ultimately leading to his downfall as he faces challenges from both law enforcement and rival criminals.