Johnny Galecki

John Mark Galecki (born April 30, 1975) is an American actor. In television, he played Leonard Hofstadter on The Big Bang Theory (2007–2019) and David Healy in 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). He was one of the highest paid television actors in the world, with his role in The Big Bang Theory earning him approximately US$900,000 per episode between 2017 and 2019…Wikipedia