Ken Kelley (born June 20, 1960) is a former American football linebacker who played two seasons in the United States Football League with the Philadelphia Stars, Chicago Blitz and Birmingham Stallions.
 He was drafted by the Philadelphia Stars in the 1983 USFL Territorial Draft.
 He played college football at Penn State University and attended Sterling High School in Somerdale, New Jersey.
The Waitress is a fictional character on the FX, now FXX series, "It's Always Sunny in Philadelphia", and is portrayed by Mary Elizabeth Ellis.
 The Waitress is a waitress at a Philadelphia coffee shop who is frequently stalked by an enamored Charlie Kelly.
 The Waitress's real name is never revealed and no one in the gang can remember it despite knowing her for several years.
Sianoa Smit-McPhee (born 21 February 1992), also known as Sianoa, is an Australian singer, songwriter and actress.
 She is best known for her years in Australian soap opera "Neighbours" as Bree Timmins.
 Her next role was in the children's television series "As the Bell Rings", which aired on the Disney Channel.
 In 2007, she appeared as Desma, the lead character in the short fantasy film "Hugo".
 From 2009 to 2011, she starred in the HBO series "Hung" as Darby Drecker.
 In 2012, Sianoa featured in the TV movie ABC "Firelight" and the series "It's Always Sunny in Philadelphia".
 The following year, she starred in "All Cheerleaders Die".
 Sianoa and her husband John Rush, a music producer, also wrote and produced the song "Take a Bite of My Heart", which was featured in the film and performed by Sianoa.
Kaitlin Willow Olson (born August 18, 1975) is an American actress and comedian.
 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.
Scott Allison Woerner (born December 18, 1958 in Baytown, Texas) is a former American football safety in the National Football League for the Atlanta Falcons and the New Orleans Saints.
 He played college football for the University of Georgia Bulldogs.
 In the 1981 Sugar Bowl, Woerner intercepted a pass by the Notre Dame quarterback in the closing minutes of the game which sealed Georgia's national championship for that year.
 He still holds several return records at the University of Georgia.
 He had the most kickoff return yards (190) in a single game (vs. Kentucky, 1977).
 He also holds the most punt return yards (488) in a season (1980).
 Woerner was drafted in the third round of the 1981 NFL Draft by the Falcons.
 He played for the Atlanta Falcons during that 1981 season.
 In 1983,1984,and 1985 he played safety for the Philadelphia Stars of the short-lived United States Football League.
 The Philadelphia Stars won 2 of the 3 USFL championships.
 The "Sporting News" selected him as a USFL All-League player both of those seasons.
Mae Laborde (May 13, 1909 – January 9, 2012) was an American television and film actress, who began her career at the age of 93 and who was active until her death at age 102.
 She was best known for her appearances on "Talkshow with Spike Feresten" as well as portraying Gladys on "It's Always Sunny in Philadelphia".
Boldly Going Nowhere was a proposed American television show for Fox.
 Rob McElhenney, Glenn Howerton, and Charlie Day, the producers and stars of "It's Always Sunny in Philadelphia", created the show along with their "Always Sunny" writers' assistant Adam Stein.
 While they did not plan to star in the show, they were the executive producers.
Alexandra Anna Daddario (born March 16, 1986) is an American actress and model.
 She is known for playing Annabeth Chase in the "Percy Jackson" film series and Blake Gaines in "San Andreas".
 She starred in the films "Texas Chainsaw 3D" and "Hall Pass", and has guest starred on series including "White Collar", "It's Always Sunny in Philadelphia", "True Detective" and "American Horror Story".
 She is also known for her part in "Baywatch" (2017), where she played the character Summer Quinn.
Alexa Demara is an American entrepreneur, actress, writer, model and martial artist.
 She is best known for her appearances on the nationally syndicated celebrity show "Extra" and "It's Always Sunny in Philadelphia".
 She also appeared in magazines such as "FHM", "MMA Sports" and "V".
 On "Extra", she was interviewed about her career on the Starsightings segment and was publicized for her charity work for the Make it Right Foundation of which Brad Pitt is a part.
 Demara also supports various animal charities.
It's Always Sunny in Philadelphia is an American television black comedy sitcom that premiered on FX on August 4, 2005.
 It moved to FXX beginning with the ninth season, and has remained there since.
 It was created by Rob McElhenney, who developed it with Glenn Howerton.
 It is executive produced and primarily written by McElhenney, Howerton, and Charlie Day, all of whom star alongside Kaitlin Olson and Danny DeVito.
 The series follows the exploits of "The Gang", a group of debauched self-centered friends who run the Irish bar Paddy's Pub in South Philadelphia.

Question: It's Always Sunny in Philadelphia stars which actress who began her career as part of the Groundlings?
Answer: Kaitlin Willow Olson