I agree with @mazingerz88. While Ledger’s performance was outstanding, and he would have most likely been nominated for an Oscar either way, his death definitely contributed to his win, and the subsequent lionization of his acting abilities in the movie. So yes, there was hype, but it was hype based on a genuinely good job in a role that had high expectations attached to it before filming even started (iconic, familiar character that everyone knows and expects to be a certain way, and Jack Nicholson’s previous stint in the role).
Now, to the second part of your question. Only five?!? Okay… Five males and five females, in no particular order.
Female villains:
1. Mrs. Iselin (Angela Lansbury) in “The Manchurian Candidate”.
2. Nurse Ratched (Louise Fletcher) in “One Flew Over the Cuckoo’s Nest”.
3. Eve Harrington (Anne Baxter) in “All About Eve”.
4. Annie Wilkes (Kathy Bates) in “Misery”.
5. Phyllis Dietrichson (Barbara Stanwyck) in “Double Indemnity”.
Male villains:
1. Senator Palpatine/The Emperor (Ian McDiarmid) in the Star Wars films.
2. Henry F. Potter (Lionel Barrymore) in “It’s A Wonderful Life”.
3.Amon Göth (Ralph Fiennes) in “Schindler’s List”.
4. Dr. Christian Szell (Laurence Olivier) in “Marathon Man”.
5. Anton Chigurh (Javier Bardem) in “No Country For Old Men”.