I've taken the liberty of ranking these. Now, who wants to marathon all of them with me?!
Darla Marks in Dazed and Confused (1993)
Memorable lines: "LICK ME! All of you!"
"Ok girlies. It's really hot out here and I'm really sick of looking at you."
What made the role great: It's always fun to watch a bitchy high school girl have a meltdown, and Parker's got plenty of those.
Source: missfancidamsel.tumblr.com
Patricia Eden in You've Got Mail (1998)
Memorable lines: "If I ever get out of here, I'm having my eyes lasered."
"I use a wonderful over-the-counter drug, Ultradorm. Don't take the whole thing, just half, and you will wake up without even the tiniest hangover."
What made the role great: Patricia is completely clueless, self-centered, and oddly ruthless. She wears all black, and tends to say exactly the wrong thing at the worst time. It's a type of New Yorker only Parker could play.
Becky St. Germaine in Spring Breakdown (2009)
Memorable lines: "I haven't been touched by a man since Clinton was in office."
What made the role great: Parker plays a bumbling nerd on spring break. That itself is epic, but there's also two scenes where she sings Wilson Phillips' "Hold On" with Amy Poehler and Rachel Dratch. Just amazing.
Source: not1but2plaids.tumblr.com
Libby Mae Brown in Waiting for Guffman (1996)
Memorable lines: "I'll always have a place at the Dairy Queen."
"What New York really is, is it's an island, with lots of people, lots of different people... I hope to maybe meet some guys, some Italian guys, and maybe watch some TV."
What made the role great: Parker is an actress playing a really terrible actress, and it's both funny and poignant. Plus, there's a lot of awesome DQ fabulousness.