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Johnny Galecki played David, the boyfriend-turned-husband of Darlene, Roseanne's younger daughter on the sitcom 'Roseanne.' After the show ended in 1997, Galecki starred in movies such as 'Vanilla Sky' in 2001 and appeared on shows such as 'My Name Is Earl' and 'Hope and Faith' before he landed his breakout role as Leonard Hofstadter on the current hit CBS sitcom 'The Big Bang Theory,' which also featured Gilbert in a recurring role.
Galecki dated his co-star Kaley Cuoco for two years. The two reportedly split in 2010.
( Photo / Wind Dancer Productions / Carsey-Werner Company / Paramount Television / ABC / CBS)