George Clooney's 5 Most Iconic Roles

Pascal Le Segretain/Getty Images

From "ER" to "Ocean's Eleven," THR takes a look at memorable roles played by the actor, who next stars in "Ides of March" and “The Descendants,” which are currently making the festival rounds.

George Clooney is making the festival rounds, with his political thriller The Ides of March kicking off Venice on Wednesday and the actor-director set to receive the Silver Medallion Tribute at Telluride this month.

Meanwhile, another movie he stars in -- The Descendants, directed by Alexander Payne -- will premiere at Telluride and close the New York Film Festival next month.

In other words, it's going to be a busy fall for Clooney.

PHOTOS: Venice Film Festival: 10 Films to Know

Here are five of the actor's most iconic roles:

ER: The actor got his big break playing Dr. Doug Ross on the NBC medical drama, leaving in 1999 after five seasons on the show to pursue a film career. In 2000, he surprised fans with an appearance for the last episode of Julianna Margulies, whose character, nurse Carol Hathaway, flew to Seattle for a reunion with Ross, her former lover and father to her twin girls. He also appeared in the series finale in 2009.

PHOTOS: The Scene at the 2011 Venice Film Festival

Out of Sight: Clooney received rave reviews for his performance in the 1998 movie, which co-starred Jennifer Lopez. He's said it's one of his favorites movies. "It was the first time where I had a say, and it was the first good screenplay I'd read where I just went, 'That's it,'" he has said. "Even though it didn't do very well box-office wise -- we sort of tanked again -- it was a really good film."

Ocean's Eleven: Clooney led an A-list cast in the movie -- and its two sequels -- playing title character Danny Ocean, a charming thief who leads a group in the multimillion-dollar burglary of a Las Vegas casino.

VENICE FILM REVIEW: 'The Ides of March'

Syriana: It might not be remembered as Clooney's highest-profile role, but the movie -- based loosely on former Central Intelligence Agency agent Robert Baer and his memoirs of being an agent in the Middle East -- won Clooney his first and (so far) only Oscar.

STORY: Venice Film Festival Gets Underway With George Clooney's 'The Ides of March'

Michael Clayton: Clooney plays a corporate "fixer" brought into to fix the situation after a lawyer has a breakdown while representing a chemical company that he knows is guilty in a multibillion-dollar class action suit. His role earned him an Oscar nom.