The emphasis of this party seems mostly on teen shows but I think my favorite bitch of all time would have to be Kate Beckinsale's Charlotte Pingress in The Last Days of Disco.
That dress is so epic, I am totally gonna cruise by Beacon's Closet on the way home and see if they have that in my size.
Other options I would consider if they didn't require fancy wigs:
Taylor Jacobsen aka Tay' from The Rachel Zoe Project.
And maybe the best toxic best friend of all time. Anna Friel as Marina in Me Without You.