updated 11:08 p.m. ET Feb. 24, 2008

Tilda Swinton built her career on offbeat and dark roles, but you’d never know it by the way she accepted the supporting-actress Oscar for her performance as an icy, immoral attorney in “Michael Clayton.”

The willowy, redheaded actress proved to be one of the liveliest winners at Sunday’s Academy Awards as she bantered about her trophy’s distinctive look.

“I have an American agent who is the spitting image of this — really, truly the same shaped head and, it has to be said, the buttocks. And I’m giving this to him because there’s no way I would be in America at all,” Swinton said, comparing the Oscar statuette to her agent, Brian Swardstrom. “I’m giving this to you.”

Swinton, who played the White Witch in 2005’s “The Chronicles of Narnia: The Lion, The Witch and the Wardrobe” and appeared in “Orlando” and “The Deep End,” also took a good-natured swipe at her “Michael Clayton” co-star.

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“George Clooney, you know, the seriousness and the dedication to your art, seeing you climb into that rubber bat suit from ’Batman and Robin,’ the one with the nipples, every morning under your costume ... on the set, off the set, hanging upside down during lunch. You rock man.”

Backstage, Swinton said she was “so stoked, as they say, I think it’s fantastic. ... I’m amazed I’m still standing. But I’m not complaining. It’s good.”

Swinton, 47, was born in London into a patrician Scottish military family. She noted that other non-American actors were taking home the gold Sunday, including Javier Bardem for “No Country for Old Men.”

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“Dude, Hollywood is built on Europeans,” she said. “Don’t tell everybody, but we’re everywhere.”

Swinton appeared taken aback when one reporter asked her about what he called her “unconventional” love life. She responded that she was raising her children with their father, Scottish artist and playwright John Byrne, while living with her “sweetheart” of three years, New Zealand painter Sandro Kopp.

“I think it’s extraordinary that we’re all really close friends,” she said.

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Swinton has appeared in dozens of films since the mid-1980s, with her choices often art-house and avant-garde projects.

She was introduced to wider audiences as the autocratic leader of an island commune in Leonardo DiCaprio’s “The Beach,” following that up with other big-name projects “Vanilla Sky,” starring Tom Cruise, and “Adaptation.”

She was a first-time nominee for “Michael Clayton.”

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