Johnny Galecki is an American actor best known for his television sitcom roles as David Healy in Roseanne (1992-1997), and as Leonard Hofstadter in The Big Bang Theory, since 2007.
His television series credits also include a recurring role in My Boys and guest appearances in Hope and Faith and My Name is Earl.
Galecki's feature film credits include Crystal, Bookies, Vanilla Sky, Bounce, Playing Mona Lisa, The Opposite of Sex, I Know What You Did Last Summer, Suicide Kings and National Lampoon's Christmas Vacation.
He received a 2007 Theatre World Award for outstanding Broadway debut for the Tony Award-nominated Broadway play The Little Dog Laughed.
His other theatre credits include The Drawer Boy and Pot Mom, at Chicago's Steppenwolf Theatre; The Member of the Wedding, for which he was nominated for a Joseph Jefferson Award; and Galileo.
Galecki was born in Belgium where his father was stationed while serving in the US Air Force. He was raised in Chicago, Illinois, and currently lives in Los Angeles.