John Mark “Johnny” Galecki (born April 30, 1975) is an American actor. He is best known for his roles as David Healy in the ABC sitcom Roseanne and Leonard Hofstadter in the CBS sitcom The Big Bang Theory.
John Mark “Johnny” Galecki (born April 30, 1975) is an American actor. He is best known for his roles as David Healy in the ABC sitcom Roseanne and Leonard Hofstadter in the CBS sitcom The Big Bang Theory.