John Mark Galecki was born in Bree, Belgium, to American parents, where his father was stationed in the U.S. Air Force. At the age of three, his family moved to Chicago, Illinois, where he grew up with his parents, Mary Lou and Richard Galecki, and siblings, sister Allison born in 1980 and brother Nick born in 1982.
His father was of Polish descent, and his mother's ancestry is Irish and Italian. His mother was a mortgage consultant, and his father became a teacher for blind veterans in a VA hospital outside of Chicago. Unfortunately, Galecki's father passed away in an accident when John was just 16 years old.
From a young age, Galecki showed a keen interest in the arts, telling his mother at just four years old, "Mom, I'm gonna be on T.V., and I don't mean when I grow up." Two years later, his parents took him to open auditions at local theaters in Chicago, where he landed his first role in "Fiddler on the Roof" and went on to receive a Joseph Jefferson Citation nomination for his portrayal of John Henry in "The Member of the Wedding" at the age of 11.
Galecki's big break came in 1989 when he was cast in the holiday film "Prancer" and later starred as Chevy Chase's son Rusty Griswold in "National Lampoon's Christmas Vacation." He also worked on the sitcom "American Dreamer" and made a guest appearance on the TV movie "Backfield in Motion" before landing the recurring role of David Healy on the hit sitcom "Roseanne."
After "Roseanne," Galecki continued to work in film and television, taking on a wide range of roles, including a dark-comedy alongside Christopher Walken in "Suicide Kings," a drug-addicted student in "Bookies," and gay characters in "Bounce" and "The Opposite of Sex." He also made guest appearances on various TV shows, including "Norm," "My Name Is Earl," and "Hope & Faith."
In 2006, Galecki returned to his theater roots, starring in the play "The Little Dog Laughed" and receiving a 2007 Theatre World Award for Outstanding Broadway Debut. He then landed the lead role of Leonard Hofstadter in the sitcom "The Big Bang Theory," which premiered in 2007 and ran for 12 seasons.
Outside of acting, Galecki is a self-proclaimed motorcycle "nerd" and enjoys riding his Harley Davidson Softail Deluxe. He is also a music lover, playing the cello and bass, and enjoys hiking with his dog Vera. Despite being a private person, Galecki has been linked to actresses Laura Harris and Kaley Cuoco. He currently resides in Los Angeles but is often spotted in his hometown of Chicago, where his siblings still live.
