Johnny Galecki is an American actor best known for his role as Leonard Hofstadter on the popular television show The Big Bang Theory. Born on April 30, 1975, in Bree, Belgium, he moved to the United States at a young age. Galecki began his acting career in the early 1990s, appearing in various television shows and films. In addition to The Big Bang Theory, Galecki has also starred in the sitcom Roseanne as David Healy. His work has earned him critical acclaim and several award nominations, solidifying his status as a prominent figure in the entertainment industry.