After graduating from Georgetown University, Cooper enrolls in the Actors Studio Drama School at The New School in New York City. While there, he lands bit parts in Sex and the City and 2001's Wet Hot American Summer.
In the ABC drama Alias, Cooper plays superspy Sydney Bristow's (Jennifer Garner) best bud Will Tippin. "I would be crossing the street, and I would hear 'Hey, Will, I love your character. I love the show,'" he tells The Boston Herald. He stars on the show for three seasons, before his character is written off the series.
As Rachel McAdams's jerk fiancé–whom Cooper describes as "kind of a sociopath"–the actor goes toe-to-toe with Vince Vaughn and Owen Wilson in Wedding Crashers. The hit comedy earns more than $200 million at the box office. That fall, Cooper returns to TV in the short-lived FOX series Kitchen Confidential.
Cooper supports Julia Roberts in her stage debut on Broadway in the drama Three Days of Rain, with Paul Rudd. "For me, opening night was like walking on the moon. It felt...like another world," he tells ABC News.
Cooper becomes summer's breakout star with The Hangover, a surprise smash that goes on to become the highest-grossing R-rated movie of all time. "It is Mr. Cooper who offers the most interesting variation on an old standard, playing his aggressive, cocky frat boy with a snarl of rage that masks anxiety," praised the New York Times. In 2010, the film wins the Golden Globe for Best Motion Picture – Comedy or Musical.
With the success of The Hangover, Cooper takes center stage – even nabbing the cover of men's style magazine Details. "I'm not even funny at all," he insists in the issue. "That's what's so ironic." The cover guy also finds himself in demand onscreen as he appears in the hit romantic comedy Valentine's Day and signs on for The A-Team, as Templeton "Faceman" Peck.
After filming the thriller Case 39, Cooper gets cozy with costar Renée Zellweger in Barcelona. Though the pair keeps their romance quiet, they're spotted together in Los Angeles and New York. "I can't say enough about her," he gushes of Zellweger. "I just love her. I [loved] coming to work. I love acting with her. I can learn so much from her." After nearly two years together, the couple calls it quits in March 2011.
Single, talented and fluent in French, Cooper is named PEOPLE's Sexiest Man Alive. "I think it's really cool that a guy who doesn't look like a model can have this [title]," the actor, 36, tells PEOPLE of the honor. "I think I'm a decent-looking guy. Sometimes I can look great, and other times I look horrifying."
After meeting on the set of The Words, Cooper and Zoë Saldana are caught sneaking kisses at a Sundance Film Festival party for their movie. "They were like two seventh graders," an onlooker tells PEOPLE. The couple cools down soon after, but briefly reunites in the fall before ultimately calling it quits again just before 2013.
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