The Green Goblin is the main antagonist of Spider-Man.
Norman Osborn first appears as the owner of Oscorp and the father of Harry Osborn. He is initially pleasent and supporting of Peter's friendship and also scientific potential, also wanting his own son to recognize his own potential. Unfortunately, his company begins to struggle, with Osborn's promised performance-enhancing serum having been hit with setbacks, not the least of which being that rodents it was tested on displayed violence, aggression, and insanity. Upon being told that his funding is on the verge of being cut, Norman becomes desperate and ultimately tests the serum on himself. The process drives him mad and he promptly murders his own scientist Doctor Stromm. He wakes up afterwards in his home amnesiac and sick.
Later, Oscorp's primary rival suffers a bombing attack, unknowingly caused by Osborn using some of his own inventions. Later, Osborn learns that his Board is expecting his resignation. Enraged at being forced out of his own company, Osborn again becomes the Green Goblin and murders the board members, also first encountering Spider-Man, who he becomes intrigued by. Waking up the next morning, Osborn at last realizes what he is doing but succumbs to the influence of his malevolent and sadistic other half. Attacking Spider-Man, he tries to convince him to join his cause, but is later rejected.
As time passes, Norman begins to lose himself more and more to the Green Goblin half of his personality, attacking and threatening May Parker to spite Spider-Man and also let him know that he is aware of his secret identity. The two's feud comes to a head when Green Goblin abducts Mary Jane and threatens to kill her, forcing Spider-Man to choose between her or a sky-cab full of innocent civilians, including children. Spider-Man however, is able to save both the sky-cab and Mary Jane, assisted by civilians who attack Green Goblin and condemn him for his threatening children's lives. Enraged, Green Goblin takes Spider-Man to a deserted area where their battle resumes. Green Goblin savagely beats Spider-Man and vows to make Mary Jane suffer as punishment for Spider-Man's "really pissing him off". However, this threat only succeeds in invigorating Spider-Man, who manages to defeat Green Goblin. Goblin unmasks himself as Norman Osborn, who begs for forgiveness from a horrified Spider-Man. Unfortunately, the Green Goblin's hold on Norman is too strong and he attempts to skewer Spider-Man from behind with his glider. Alerted to it by his Spider-Sense, Spider-Man moves out of the way and Norman is impaled by his own glider. Right before he dies, Norman, at last freed from the Green Goblin's control, begs Peter to not tell Harry the truth. Though deceased and redeemed, the malevolent half of Norman Osborn would live on as a figment of Harry Osborn's imagination, goading him to continue his father's legacy and seek vengeance on Spider-Man.
Here's the real truth: there are eight million people in this city, and the teeming masses exist for the sole purpose of lifting the few exceptional people on to their shoulders. You, me, we're exceptional. I could squash you like a bug right now. But I'm offering you a choice: join me! Imagine what we could accomplish together...what we could create. Or we could destroy! Cause the deaths of countless innocents in selfish battles again and again and again until we're both dead! Is that what you want? Think about it hero!"-Green Goblin attempting to convince Spider-Man to join him.
◾"Misery, misery, misery that's what you've chosen. I offered you friendship, and you spat in my face!"-Green Goblin as he attacks and beats Spider-Man.
◾"You've spun your last web Spider-Man. Had you not been so selfish your little girlfriend's death would have been quick and painless, but now that you've really pissed me off, I'm gonna finish her nice and slow. MJ and I...we're gonna have one hell of a time!"-Green Goblin threatening to kill Mary Jane after subduing Spider-Man.
◾"God-speed Spider-Man"-Green Goblin right before he's killed by his own glider.
◾"Peter...don't tell Harry."-Norman Osborn's last words.