If you knew him at all, you knew him as Sam "Ace" Rothstein, the character Robert De Niro played in the 1995 movie, "Casino."

His real name was Frank "Lefty" Rosenthal. He was a sports-betting pioneer. And he really was the stuff of legends.

Rosenthal, who died of a heart attack in Miami Beach Monday at 79, ran four Las Vegas hotel casinos simultaneously in the 1970s and early 1980s - without having a valid Nevada gaming license.

Everyone knew he was mobbed up, but he had his own TV show - whose guests included Frank Sinatra and Bob Hope.

He could be ruthless.

He admitted to The Miami Herald that he ordered his security crew to crush the right hand of a card cheat he caught at the now-defunct Stardust Hotel - just as De Niro's character did in "Casino."

Even though he ran a sports book from the Stardust, he survived numerous arrests and indictments for fixing football and basketball games.

He got the nickname "Lefty" because he took the Fifth Amendment 38 times during a 1961 US Senate hearing - keeping his left hand up continuously while doing it.

"He's one of the originals," Nick Pileggi, the author and screenwriter of "Casino," said yesterday. "When Lefty went down, the new Las Vegas emerged. The corporate Las Vegas."

Frank Lawrence Rosenthal was born in 1929 in Chicago.

A one-time hot-dog stand owner, he formed an early association with Anthony Spilotro ("Tony the Ant"), who in the 1960s was linked to bribery attempts on university basketball and football players.

In 1971, the Chicago mob picked Spilotro to succeed veteran mobster Marshall Caifano as its Las Vegas representative, and he and Rosenthal joined forces in Sin City.

Rosenthal was the brains. Spilotro, played by Joe Pesci in the Martin Scorsese-directed movie, was the muscle.

It was part of Rosenthal's mythology that when he arrived in Vegas, he was busted and told by a top cop, "You and your Chicago friends aren't welcome in this town. I want you to catch the next flight out of here and don't come back."

It never happened.

Rosenthal became a sports-gambling pioneer and secretly ran the Stardust, Fremont, Hacienda and Marina casino hotels.

Eventually, Nevada authorities discovered that Rosenthal was running casinos without a state license, and in 1976, the Nevada Gaming Control Commission held a hearing to determine if Rosenthal was fit to hold one.

The board denied Rosenthal a license, but he appealed and won.

The decision was only overturned in 1988, when the state of Nevada placed him in its "black book," banning him in or near any casino.

Still, Rosenthal boasted that he slipped in and out of Sin City wearing disguises.

Unlike many of his associates, he was able to avoid a violent death.

In 1982, he survived a car bombing of his Cadillac Eldorado outside a Las Vegas restaurant. A metal plate under the seat - there is a debate as to whether it was installed as personal armor - saved his life.

Rosenthal was taken to a local hospital with minor burns on both legs, his left arm and on the left side of his face.

True to his code, he refused to sign a crime report or discuss the matter with cops.

Rosenthal and Spilotro fell out after the latter began an affair with Rosenthal's wife, Geri, a casino hustler.

In 1986, Spilotro and his brother, Michael, were killed by being buried alive as part of mob wars in Chicago.

Geri, who inspired a character played by Sharon Stone in "Casino," eventually abandoned Rosenthal and died of a drug overdose.

After being placed in the black book, Rosenthal left Las Vegas and settled in Florida, handicapping sports events, running a gambling Web site and serving as a consultant for offshore casinos.

In a 2005 interview with the Miami Herald, he described giving the order to crush the right hand of the card shark.

"He was part of a crew of professional card cheats, and calling the cops would do nothing to stop them, so we used a rubber mallet - metal hammers leave marks, you know - and he became a lefty," he said.

"I didn't care if they tried to scam other houses, I just wanted to make it clear that they couldn't do it at mine."

Rosenthal denied he was a frontman for the mob.

"I ran my casinos. The mob had nothing to do with my casinos," said the gambler, claiming he got a job at the Stardust by filling out an application.

"As the CEO for four casino properties, and with the consent of the chairman of the board, those properties maintained the very highest industry standards."

Rosenthal said his secret was merging street smarts with advanced statistics and probability.

"You can make the odds work in your favor when you study gaming as a science," he said.

andy.geller@nypost.com