Johnny Galecki in The Big Bang Theory 9-09 "The Platonic Permutation"

Johnny Galecki shirtless in The Big Bang Theory 7-08 "The Itchy Brain Simulation"

Johnny Galecki shirtless in The Big Bang Theory 5-22 "The Stag Convergence"

Johnny Galecki shirtless in The Big Bang Theory 5-13 "The Recombination Hypothesis"

Johnny Galecki shirtless in The Big Bang Theory 5-02 "The Infestation Hypothesis"

Johnny Galecki shirtless in The Big Bang Theory 4-21 "The Agreement Dissection"

Johnny Galecki shirtless in The Big Bang Theory 4-18 "The Prestidigitation Approximation"

Johnny Galecki shirtless in The Big Bang Theory 3-05 "The Creepy Candy Coating Corollary"