Johnny Galecki

John Mark Galecki was born on April 30, 1975, in Bree, Limburg, Belgium, to American parents of Polish, Irish, and Italian descent. His father, Richard Galecki, was a U.S. Air Force member stationed in Belgium who later worked as a rehabilitation teacher, and his mother, Mary Louise Noon, was a mortgage consultant. The eldest of three children, Galecki has a sister, Allison, and a brother, Nick. The family settled in Oak Park, Illinois, where Galecki grew up. He left formal schooling after the eighth grade, attending high school for only a single day.

Galecki began his career in the Chicago theatre scene as a young child before making his onscreen debut in the 1987 CBS miniseries Murder Ordained, which also featured JoBeth Williams and John Goodman. Two years later, he appeared in both Prancer and National Lampoon's Christmas Vacation, in which he portrayed Rusty Griswold. In 1990, he was cast as Danny Nash on the NBC comedy American Dreamer, and the following season joined the ABC sitcom Billy, a spin-off of Head of the Class. During his time on Billy, he began making guest appearances on Roseanne as Kevin Healy — a character whose name was quickly changed to David — and was made a permanent cast member from the fall of 1992 following Billy's cancellation. Galecki remained on Roseanne through the end of its run in 1997, with his character eventually marrying Darlene Conner and fathering two children with her. He reprised the role in the 2018 ABC revival of Roseanne and continued appearing as David on the subsequent spinoff The Conners, which premiered in October 2018.

Following Roseanne's original conclusion, Galecki took on roles in a number of films, including Suicide Kings (1997), I Know What You Did Last Summer (1997), Bookies (2003), In Time (2011), and Rings (2017). He also appeared briefly in the 2008 superhero comedy Hancock and played a parody version of himself in three episodes of Entourage in 2011. In 2005, he appeared in a pilot for a U.S. adaptation of the British sitcom Peep Show, portraying Mark Corrigan.

Galecki's Broadway career centers on his work in The Little Dog Laughed by Douglas Carter Beane. He originated the role of Alex, a male prostitute, when the play premiered at Second Stage Theater in 2006, and carried the role into the production's Broadway run at the Cort Theatre in late 2006 and early 2007. His performance earned him a Theatre World Award in 2007.

From 2007 to 2019, Galecki starred as Leonard Hofstadter on the CBS sitcom The Big Bang Theory, a role he advocated for himself after initially being approached to play Sheldon Cooper — a part that ultimately went to Jim Parsons. The series ranked among the top three most popular television comedies in the United States for most of its run. Galecki, Parsons, and co-star Kaley Cuoco each earned $325,000 per episode until 2013, rising to $1 million per episode by 2014. Between 2017 and 2019, Galecki earned approximately $900,000 per episode. In 2018, Forbes estimated his annual earnings at $25 million, ranking him the world's second highest-paid male television actor that year, behind Parsons. The accolades he received for his work include a Satellite Award, along with nominations for a Primetime Emmy Award, a Golden Globe Award, and six Screen Actors Guild Awards. Galecki is also a cellist, a skill incorporated into his portrayal of Leonard on the show.