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 (1992–1997; 2018) 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). Wikipedia
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 (1992–1997; 2018) and The Conners (2018–2019). Galecki also appeared in the films Prancer (1989), National Lampoon's Christmas...