Kaitlin Olson had major roles in all the companies she has been part of.
Kaitlin Olson . She began her career in the Groundlings , an improvisational group in Los Angeles , California , and had minor roles in several television series before being cast as Deandra `` Sweet Dee '' Reynolds on the FX black comedy series It 's Always Sunny in Philadelphia in 2005 . Olson has also appeared in film , with roles in Leap Year ( 2010 ) , The Heat ( 2013 ) , and also provided the voice for Destiny in Finding Dory ( 2016 ) .