Raj is an astronomer and an astrophysicist, not a theoretical physicist, and he’s there for cultural and psychotic diversity. He’s the only thing keeping the show from becoming Nerd Friends.
And his sister is pretty.
Yes, she is! I wasn’t that crazy about her character, but the actress who plays Priya certainly is drop-dead gorgeous!
I wonder if we have seen the last of her?
And speaking of sisters, who played Sheldon’s sister (from a previous season / episode, don’t know which)? She was very hot!
Courtney Henggeler played his fraternal twin sister, Missy.
in season 01 episode 15 The Pork Chop Indeterminacy.
the boys were impressed.
And so was I! Thanks for the info.
I certainly hope so. She wasn’t that good looking (the other three women put her in the shade) and I hated the character.
I’d say with the hottest first, the list goes Penny, Missy, Priya, Bernadette, Amy. 
The funny thing is, I actually overheard a conversation a few days ago while out at lunch --two guys were talking about Mayim Bialik, the actress who plays Amy Farrah Fowler. One thought she was ugly, and the other one was saying that she wasn’t really ugly, she was just “plain”. They both thought that she was smart and funny, though!
I have a new prediction: The finale is Howard and Bernadette eloping.
I think she’s just adorable.
A couple of weeks ago when Sheldon knocked one out of the park by buying her a tiara, her reaction left me utterly smitten.
SMITTEN, I TELLS YA! 
My rankings: Priya, Danicka Mckellar (forgot character name), Bernadette, Penny, AFF.
If we start counting guest stars, the list will get very long, and Priya will still be at the tail end of it.
So let it be written. So let it be done.
Yeah, I really don’t like her.
Danica McKellar played Abby.
And the one who played her friend wasn’t exactly a dog either.
That would be Jen Drohan as Martha.
For geeks, the guys regularly score some amazing women. Smart must really be the new sexy.
Well, I see extremely attractive college-age girls strolling around with nerdy-looking guys quite often (I work at a university), so perhaps it is true that “smart is the new sexy”. Or perhaps the guys that I see walking with the sexy gals just come from wealthy families. Ha!
Wait, Danica McKellar was on the show? Who’s Abby?
She was a guest star as a girl who drunk-Raj was macking on at a faculty party. He dragged Sheldon along as a wingman.
It was season 3 Episode 12 “The Psychic Vortex”.