1. Amy Farrah-Fowler (Mayim Bialik)
"Zack, I am Amy Farrah Fowler. We met the other night. I have spent my life in pursuit of pure knowledge. Until I met you, my decisions were founded in logic and reason. And yet here I stand before you, 130 pounds of raging estrogen, longing to grab hold of your gluteus maximus, and make Shakespeare's metaphorical beast with two backs." The introduction of Amy Farrah-Fowler was game changing for the show. It was immediately apparent that Amy Farrah-Fowler was Sheldon's female equivalent and the wonderfully weird match I assumed he'd never find. Amy Farrah-Fowler went from one-time internet date to serious relationship material in record time and soon became a principal cast member. Even in spite of their characters having a disturbingly graphic row about whether her or Sheldon's research was more significant. 'Defecating Clark Maxwell' was not one of the more delicate lines the show has ever seen. Amy is a well written character and the drastic change in her personality from a 'female Sheldon' to a sex-crazy socialite was a smooth one, if a little bit rushed. Aside from the quick, witty, observational dialogue and the character's vulnerability, the secret to Amy's show stealing is the actress behind her - Mayim Bialik - who is gifted with the ability to create humor and dominate a television comedy.