Kaitlin Olson is an American actress best known for her leading role as Deandra "Sweet Dee" Reynolds on the television comedy series It's Always Sunny in Philadelphia, since 2005.
Olson starred in the romantic comedy Leap Year as Libby, best friend to Amy Adams' character Anna.
She also starred in the independent film Weather Girl, winner of the Best Film Award at the 2009 Vail Film Festival. Olson played a morning show co-host opposite Mark Harmon. The ensemble cast also included Jane Lynch, Jon Cryer and Blair Underwood.
Olson has been praised for crafting unique and memorable characters that recur on several shows. On Curb Your Enthusiasm, she plays Larry's sister-in-law Becky. On FX's The Riches, she played the one-armed neighbour Hartley Underwood. And on The Drew Carey Show, she was Mimi's nemesis Traylor for two seasons.
Other television credits include Miss Match, The George Lopez Show and Out of Practice.
Also known for her improv talent, Olson began her career with a highly coveted spot in The Groundlings Sunday Company, a training ground for such comics as Will Ferrell and Phil Hartman.
The showcase led to her casting in several improv/hidden camera shows, including Punk'd, The Jamie Kennedy Experiment and Meet the Marks. She was also a series regular on FOX's Kelsey Grammer Presents: The Sketch Show.
Olson was born and raised in Tigard, Oregon, and graduated from the University of Oregon with a degree in Theatre Arts.
She lives in Los Angeles with husband Rob McElhenney, and their dog Oscar.