"Oh my gosh! What an incrdible year to be nominated," said Winslet, who played Joanna Hoffman, an early Apple team member and confidante to Steve Jobs, said onstage, giving shoutouts to her costar Michael Fassbender ("I would watch you every day and be completely blown away"), her fellow nominees and her real-life leading man, husband Ned Rocknroll: "My wonderful husband Ned who gave his seat to my mum so she could sit next to me. Ned, you're in this room, I know you are. Hi babe, Happy Valentine's Day! And my children who are probably more excited about this than I am. And my wonderful parents. I love you so much."
She edged out Oscar frontrunner Alicia Vikander, along with Jennifer Jason Leigh, Rooney Mara and Julie Walters. The Danish Girl star Vikander won the Screen Actors Guild award last month, while Winslet nabbed the Golden Globe.
Meanwhile, Mark Rylance won the BAFTA, Britain's highest film honor, for best supporting actor for Bridge of Spies, making one of the most unpredictable Oscar races even tighter.
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Sylvester Stallone (who wasn't nominated for a BAFTA) won the Golden Globe and Idris Elba (who's not nominated for an Oscar) earned the Screen Actors Guild award.
Director Steven Spielberg accepted the award for Rylance, who's performing onstage in New York City in the play Nice Fish, which he co-wrote.