Leonard Hofstadter
Leonard Hofstadter was an experimental physicist who shared an apartment with his best friend, Dr. Sheldon Cooper. The romance between Leonard and his next-door neighbor, Penny, was a driving force in the series. Leonard's character was named after actor Sheldon Leonard and Nobel Prize in Physics Laureate Robert Hofstadter.
Played by Johnny Galecki
Johnny Galecki was also plucked from the '90s sitcom Roseanne, but his performance on The Big Bang Theory earned him several award nominations. In 2018, Galecki was estimated to be the second-highest-paid in the world TV actor by Forbes.