The Green Goblin!

Real Name: Norman Osborn II
First Appearance: Amazing Spider-Man 14
Died In: Amazing Spider-Man 122, after being impaled by his own goblin glider, and again in flames during the end of the clone saga in Spider-Man 75. But he's back again...looks like The House of Ideas is running out of 'em!
Powers: Osborn used an untested experimental formula on himself that gave him super-human strength, increased his intellect and, according to the current lame-o retcon, granted him a Wolverine-like "healing factor" that permits recovery after major organs have been obliterated by a goblin glider through the chest. Modified versions of this formula, evidently minus the healing factor, have been used by lots of people since then, including the original Hobgoblin and Osborn's own son, Harry.

What's His Problem? Oh, the untested experimental formula I mentioned? It slowly drove him insane. When he was plain Norman Osborn, ruthless industrialist, he had no interest in Spider-Man. But as the Green Goblin, he developed a psychotic hatred for his foe that eventually eroded his criminal judgment and put paid to his dream of running the New York underworld.
Favorite Quote: "Nobody can say I wasn't a perfect father, do you hear..? Nobody !" (Amazing Spider-Man 40, when an unmasked Goblin is explaining his motivations to an equally-unmasked Spider-Man. Meanwhile, the panels are demonstrating how Osborn alternated between showering his son with expensive gifts and ignoring him completely.)
Heroes He Kept Running Into: Goblins and Spider-Men just seem to be natural enemies, although Osborn once got chased off by the Human Torch and, on another occasion, wandered into a cave that held the Incredible Hulk. Talk about your wrong turns!
People Who Think He's Not So Bad: Osborn was worshipped by his son, Harry. And Peter Parker could tolerate him when he wasn't being homicidal.
Most Despicable Act: The murder of Peter Parker's girlfriend Gwen Stacy in Amazing Spider-Man 121. (Some say that's actually Marvel's most despicable act!)
Hey, What About the Goblin's Return? I have nothing to say about the Goblin's return, largely because my pal Greg Helton says it all as far as I'm concerned: "Marvel was in trouble for bringing back a character that died 21 years ago, so they solve the problem by bringing back a character that died 23 years ago?! Whose brilliant idea was that?"