Aired Friday March 1, 2:00pm - 2:30pmon E4

The Big Bang Theory

Series 2 Episode 20: The Hofstadter Isotope

Leonard is devastated when the geeky sales clerk in a comic book store hits on Penny. Even worse, she doesn't mind! Leonard can't believe that Penny would date one of `them', unless it is him. Sheldon tries to scupper the budding romance by constantly challenging the clerk to engage in dialogue from Batman.

Original air date
Cast and crew
  • Johnny GaleckiLeonard Hofstadter
  • Jim ParsonsSheldon Cooper
  • Kaley Cuoco-SweetingPenny
  • Simon HelbergHoward Wolowitz
  • Kunal NayyarRaj Koothrappali
  • Kevin SussmanStuart Bloom