American actress and comedian (born 1975)
Source (Wikipedia): Kaitlin Olson

Kaitlin Willow Olson McElhenney is an American actress. She began her career in the Sunday Company at the Groundlings, an improvisational theatre and school in Los Angeles. She had minor roles in several television series before being cast as Deandra “Sweet Dee” Reynolds on the FX comedy series It’s Always Sunny in Philadelphia (2005–present).