It's Always Sunny in Philadelphia stars which actress who began her career as part of the Groundlings?
It's Always Sunny in Philadelphia:  It is executive produced and primarily written by McElhenney, Howerton, and Charlie Day, all of whom star alongside Kaitlin Olson and Danny DeVito. Kaitlin Olson: Kaitlin Willow Olson (born August 18, 1975) is an American actress and comedian.
Kaitlin Willow Olson