Source: writeups.com

7. Kraven the Hunter

(Spider-Man, Marvel Comics)

Sergei Kravinoff was a big game hunter who always sought bigger quarry. After years of this, he thought he'd found the world's greatest prey. Not a Spider. Not a Man. But a Spider-Man.

Kraven went full supervillain, going after Spider-Man in earnest. He pulled every last trick to get Peter Parker, and he always came away empty-handed. This slowly drove him insane, which led into one of the darkest Spider-Man stories of all time.

In Kraven's Last Hunt, Kraven tracked Spider-Man down, beat him, buried him alive, wore his costume, and shot himself in the head. He also ate some spiders. It was creepy, but that's how Kraven the Hunter went out. With maybe the best comic he’d ever been in. It was the platonic ideal of how to kill off a character. He even got replacements. He had a son, a daughter, a wife. All of them showed up to fight Spider-Man and others. Perfect! We get a Kraven, but Sergei’s dead.

But then came The Grim Hunt, a good story that unfortunately brought Kraven right back.