John Mark "Johnny" Galecki (born April 30, 1975) is a Belgian-born American actor. He is best known for his roles as David Healy in the sitcom Roseanne, Rusty Griswold in National Lampoon's Christmas Vacation, and as Leonard Hofstadter, PhD, in the CBS sitcom The Big Bang Theory. Description above from the Wikipedia article Johnny Galecki, licensed under CC-BY-SA, full list of contributors on Wikipedia.

• The Big Bang Theory (2007)

  
• Hancock (2008)

  
• In Time (2011)

  
• Bean (1997)

  
• I Know What You Did Last Summer (1997)