John Mark Galecki is an American actor. He played Leonard Hofstadter in the CBS sitcom The Big Bang Theory (2007–2019) for which he received a Primetime Emmy Award nomination, and David Healy in the ABC sitcoms Roseanne and The Conners (2018–2019). Galecki also appeared in the films Prancer (1989), National Lampoon's Christmas Vacation (1989), Suicide Kings (1997), I Know What You Did Last Summer (1997), Bookies (2003), In Time (2011), and Rings (2017).

Prancer is a 1989 Christmas fantasy drama film directed by John Hancock, written by Greg Taylor, and starring Rebecca Harrell, Sam Elliott, Cloris Leachman, Abe Vigoda, Michael Constantine, Rutanya Alda, John Joseph Duda, and Ariana Richards. It is set in Three Oaks, Michigan, where town exteriors were filmed. Filming also occurred at the Old Republic House in New Carlisle, Indiana, La Porte, Indiana, and at Starved Rock State Park in Utica, Illinois.