Johnny Galecki, known for his role as Leonard in The Big Bang Theory, initially found success in the sitcom world with his role as David Healy in Roseanne. After Roseanne ended, Johnny wasn't actively looking for another sitcom role but was intrigued by the opportunity to play Leonard. Although he was initially considered for the role of Sheldon, he ultimately chose to portray Leonard after seeing Jim Parsons' incredible performance. Johnny immersed himself in character development, even visiting UCLA to learn about physics. Since The Big Bang Theory ended, Johnny has had few projects, with a focus on his personal life and being a dad.