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Kaitlin Olson, 'It's Always Sunny in Philadelphia'
"It's Always Sunny in Philadelphia," FX
You know her as: Dee, Dennis' (Glenn Howerton) sister, sometime steroid abuser and occasional crackhead
Why we like her: Although she's typically the most sane -- or maybe the least insane -- of the "Philadelphia" crew, Dee is sometimes as prone to extremism in the pursuit of happiness as her brother and his boys Mac (Rob McElhenney) and Charlie (Charlie Day). The episodes from this season where Olson (shown with TV dad Danny DeVito) trained to be a boxer and, along with Dennis, went on welfare and became a drug addict, showed off a strong gift for physical comedy.
Where else you've seen her: Olson has done multiple episodes of "Curb Your Enthusiasm" and "The Drew Carey Show" and was a cast member of Kelsey Grammer's "The Sketch Show" on FOX.