Kaitlin Olson Kaitlin Olson

She plays Deandra "Sweet Dee" Reynolds, foulmouthed girl Friday to the barfly doofuses of It's Always Sunny in Philadelphia.

Where you've seen her before Most recently, as Amy Adams' sister in Leap Year. Before that, the Groundlings grad killed it as Cheryl Hines' sister on Curb Your Enthusiasm and as the passive-aggressive, one-armed neighbor on The Riches. "I loved that character," says Olson. "She was totally weird."

Why we love her Imagine Carol Burnett crossed with Tina Fey and vodka. For six seasons, Olson has more than held her own with the Sunny boys' club while giving us the sexiest, funniest gal pal since Seinfeld's Elaine Benes.

It's always sonny Olson's real-life pregnancy — she and hubby (and costar) Rob McElhenney had a baby boy this summer — will be milked for major laughs this season, starting with tonight's Halloween whodunit episode all about the bun in Sweet Dee's oven. Filming in the family way meant curtailing the physical comedy: "I couldn't ram my head into any car doors this season," says Olson, "which was a huge disappointment for me personally."

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