Maybe in character terms, but as far as the visual aspect goes, it's gotta be Theda Bara.

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Lily Munster will always be the hottest goth babe ever:

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I dig the sexy bat necklace.

Lily DID pretty much perfect the look.

Fuck me. It's Helena Bonham Carter.

Having watched both the Munsters and the Addams Family, I'd have to say that the Addams' work better with me. Not quite so goofy, and more... twisted. But that was all right, as it worked in the dark and evil world that the Addam's and their kin lived in. Had I a choice, I'd get adopted by them in a second.

Morticia: So... you still desire me after all these years? The old ball and chain?
Gomez: Forever!
Morticia: I'll get them!
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Dr. Pinderschloss: Oh, my little bundle. So much you don't understand. The human spirit, it is a hard thing to kill.
Grandmama: Even with a chainsaw!

Oh, the Addams Family was a much better show, but the Munsters wasn't bad for a knockoff. Grampa was cool, and in high school I knew a few guitar players who enjoyed playing fuzzed up versions of the theme music.

but this man is cool:
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Uncle Fester: Dementia, what a beautiful name.
Dementia: It means "insanity."
Uncle Fester: My name is Fester. It means "to rot."

“When the famous Diana of Poitiers became the mistress of Henry II, she was a widow, and the complaisant court not only made her mourning-colours the favourite fashion, but adopted the most lugubrious fancies for personal decoration.”

“Rings in the form of skeletons clasped the finger; other mementos of an equally ghastly description were used as jewels; small coffins of gold contained chased and enamelled figures of death; and watches were made in the form of skulls…” (source here).