Great list! I was dropping in to post Gene Tierney in Leave Her to Heaven. What a Class A bitch!
I’ll also nominate your namesake Eve in All About Eve. She’s a real piece of work too!
How about Shrek 2’s Fairy Godmother?
Plus also the Trunchbull from Matilda.
Witch Hazel from Looney Tunes.
Maleficent! She gets my vote. She has a bad attitude (wants to kill a kid for what seems like no reason), a bad familiar (a raven), and can turn into a dragon. Awesome.
Meridith from Disclosure.
The Other Mother.
Aunt Ester!
The mom in Carrie
The mom in Sybil
The mom in Sleepaway Camp
An honorable mention, at least, should go to Livia Soprano, too.
Nurse Ratched is the only possible nominee for the top slot in this category, IMO. Pure Satan.
Not to argue, but she’s #2 behind Agent Stahl! 
Livia from I, Claudius is an obvious choice, as is Milady Winter. I’m glad to see the Baroness from Paul Park’s A Princess of Romaniagetting a mention in this thread: I’ve only read the first book in that series, but I liked her more than the main characters.
Let me think of a few great female villains that haven’t been mentioned yet (if they have and I missed them, I apologize in advance):
Mahaut, Countess of Artois from Les Rois Maudits: Scheming and powerful matriarch who reminds me of Livia in some ways. Haven’t finished the books yet, but the rivalry between the countess and her equally ruthless nephew is fascinating to read about.
Demona from Gargoyles: One of the most tragic characters I can think of in the realm of animation. Deep down, Demona knows that she screwed up badly, but she can’t deal with her guilt and thus lashes out at innocents instead. As despicable as some of her actions are, it’s hard not to feel at least a bit of pity for her in certain scenes.
Snoop from The Wire: Equal parts funny and menacing, she and Chris made a great team and were always a joy to watch.
“Snoop from The Wire: Equal parts funny and menacing, she and Chris made a great team and were always a joy to watch.”
Great choice! One of my favorite characters from one of my favorite shows. The scene where she buys the nail gun is a classic.
Along with Maleficent and several of the others already mentions, Ursula the sea witch from Disney’s The Little Mermaid.
I think one measure of how villainous a character is, is if you find yourself in their sites, do you think “Oh, shit!”? If so, Ursula definitely counts for me.
So many fantastic choices so far. I have always loved Maleficent. Even when I was a girl, Sleeping Beauty was my favorite Disney movie because of that awesome dragon scene.
Miss Umbrage and Lestrange are both excellent choices as well.
For a new nominee I name Miss Parker from The Pretender. First couple of seasons only. They tried too hard to make her a sympathetic character in later seasons. She was best when she was just tough, evil, and you just vaguely felt sorry for her in the scenes with Daddy.