The Big Bang Theory

The Alien Parasite Hypothesis (Season 4, Episode 10)

TV-PG

TV Episode | 20 min | Comedy, Romance

Amy finds she has sexual feelings for Penny's ex-boyfriend Zack, while Raj and Howard try to prove who would be the better superhero.

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Cast	+ Add Cast
8 cast members

Name	Known for
Johnny Galecki Leonard Hofstadter Leonard Hofstadter See fewer	The Big Bang Theory (2007)
Jim Parsons Sheldon Cooper Sheldon Cooper See fewer	The Big Bang Theory (2007)
Kaley Cuoco Penny Penny See fewer	The Big Bang Theory (2007)
Simon Helberg Howard Wolowitz Howard Wolowitz See fewer	Florence Foster Jenkins (2016)
Kunal Nayyar Raj Koothrappali Raj Koothrappali See fewer	The Big Bang Theory (2007)
Mayim Bialik Amy Farrah Fowler Amy Farrah Fowler See fewer	Beaches (1988)
Melissa Rauch Bernadette Rostenkowski Bernadette Rostenkowski See fewer	The Big Bang Theory (2007)
Brian Thomas Smith Zack Johnson Zack Johnson See fewer	The Big Bang Theory (2007)