A comic book character, first published in 1969 by Warren Magazines and written by none other than science fiction legend Forrest J. Ackerman. Warren had always been best known for publishing horror comics, usually in an oversized, black-and-white format similar to Mad Magazine. Vampirella was Warren's first-ever continuing character -- most of their previous stories, in magazines like the classic "Creepy", were short, self-contained, and focused on a different cast for each terror tale, similar to the ones in the old EC Comics of decades past.
Forrey Ackerman wrote the first Vampirella story, but Archie Goodwin took over scripting chores in the next issue and is usually credited toward doing the most to develop the character and her supporting cast. The best known artists in the early years of the series were Tom Sutton and José Gonzales, with covers created by fantasy artist Frank Frazetta.
So who was Vampirella? She was a beautiful brunette from the planet Drakulon, where the rivers flowed with blood instead of water. She was -- surprise, surprise -- a vampire. She could sprout bat wings, she was supernaturally strong and fast, and she drank blood. But she was a good vampire, and when she got stuck on Earth, she made friends with a bunch of Earthlings and went about fighting and killing supernatural monsters, including vampires, werewolves, and even giant octopi! And that's why Vampi was so damn popular -- she was a vampire, and she devoted her life to killing other vampires.
Either that, or horny teenaged guys liked her costume.
See, her costume was almost nonexistent -- a thin, ribbon-like swath of red material that climbed up from her crotch, "covered" her breasts, then attached to a miniature white "Dracula" collar. There was also a little gold bat insignia right over her crotch -- that was the only place where there was enough material to put an insignia, see? Anyway, Vampi should've fallen out of that costume every other step she took -- which would've been great for sales of the book, too. Even more incredibly, no other characters ever commented on how skimpy her uniform was. At some point, someone should've gasped or pointed or complained or offered her a C-note, but noooo... Anyway, Frazetta usually gets credit for creating the costume, though there's some indication that Trina Robbins may have helped with the design, too.
Anyway, Vampirella's book appeared regularly until 1983, when Warren quit the publishing biz. Harris Publications bought the rights to the character, but really didn't do anything with her until 1992, when they started publishing a new Vampi comic, this time in full color. They've also created a new origin for her, explaining the old story away as being a bunch of artificial memories. According to the Harris continuity, Drakulon wasn't another planet -- it was actually part of Hell! Now, rather than destroying vampires because she's a good vampire, Vampi had been given a holy quest to get rid of all Earth's vampires, who were created by her evil mother Lilith. Vampi also discovered she was a new kind of vampire, with no weaknesses to sunlight, crosses, holy water, garlic, or having to count sesame seeds. (All in all, the original origin was better.)