Missy Cooper was a decent minor character on the show. She’s actually Sheldon’s twin sister but their personalities and intelligence could not be any different.
She’s definitely too skinny for my taste but I will admit she’s quite pretty. And what does Sheldon’s friends do? Try to hit on her. And this was the prime time for Howard and Raj to be as creepy as they ever got.
I do remember her showing back up when Sheldon got married to Amy Farrah Fowler. Missy apparently got pregnant and baby daddy is out of the picture. Which isn’t uncommon (but ironic) in the conservative South.