The Big Bang Theory

The Alien Parasite Hypothesis

Series 4 - Episode 10 The Alien Parasite Hypothesis



Amy finds she has romantic feelings for Penny's former boyfriend Zack, while Raj and Howard begin competing to prove which of them would make the better superhero. Comedy, guest starring Brian Thomas Smith.

Cast & Crew

Leonard Hofstadter Johnny Galecki
Sheldon Cooper Jim Parsons
Penny Kaley Cuoco
Howard Wolowitz Simon Helberg
Raj Koothrappali Kunal Nayyar
Amy Farrah Fowler Mayim Bialik
Zack Brian Thomas Smith
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