April 30, 1975
From Wikipedia, the free encyclopedia
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.
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