Johnny Galecki was born to his American parents in Belgium when his father was stationed there with the U.S. Air Force. After growing up in Illinois, he got his first major role as the son, Rusty, in National Lampoon's Christmas Vacation. While that role changed actors every movie, Galecki was able to land a part in Rosanne as Darlene's boyfriend (and later husband).
As no stranger to sitcoms or working with Chuck Lorre, he'd one day be cast as the starring role of Leonard in The Big Bang Theory.
Leonard: So don't watch TV. Read a book.
Sheldon: And be a social pariah? Now you know that's not my style.
Birthplace: Bree, Belgium
Birthday: April 30, 1975