Thomas Christopher Parnell is an American actor and comedian. First breaking through as a performer with the Los Angeles comedy troupe The Groundlings, Parnell found wider success during his tenure as a cast member on the NBC sketch comedy series Saturday Night Live from 1998 to 2006. After leaving SNL, he played the role of Dr. Leo Spaceman on the NBC sitcom 30 Rock (2006–2013). In animation, he voices the narrator on the PBS Kids series WordGirl (2007–2015), Cyril Figgis on the FX series Archer (2009–2023), Jerry Smith on Adult Swim's Rick and Morty (2013–present), and Doug on Fox's Family Guy (2019–present). He also voices "The Progressive Box" in a series of advertisements by the Progressive Corporation.

The Groundlings is an American improvisational and sketch comedy troupe and school based in Los Angeles, California. The troupe was formed by Gary Austin in 1974 and uses an improv format influenced by Viola Spolin, whose improv techniques were taught by Del Close and other members of the Second City, located in Chicago and later St. Louis. They used these techniques to produce sketches and improvised scenes. Its name is taken from Shakespeare's Hamlet, Act III, Scene II: "...to split the ears of the groundlings, who for the most part are capable of nothing but inexplicable dumbshows and noise." In 1975 the troupe purchased and moved into its location on Melrose Avenue.