The Big Bang Theory/The Alien Parasite Hypothesis
| This article about an episode needs to be expanded with more information.|
Please help out by editing it.
The Alien Parasite Hypothesis is the tenth episode of the fourth season of The Big Bang Theory, and the seventy-third episode overall.
Starring: Johnny Galecki (Dr. Leonard Hofstadter), Jim Parsons (Dr. Sheldon Cooper), Kaley Cuoco (Penny), Simon Helberg (Howard Wolowitz), Kunal Nayyar (Dr. Rajesh "Raj" Koothrappali), Mayim Bialik (Amy Farrah Fowler), Melissa Rauch (Bernadette Rostenkowski)
Guest Starring: Brian Thomas Smith (Zack)