These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Norman Osborn
Alternative Character Interpretation: Originally and for most of his history, Osborn has been treated as a sympathetic Tragic Monster. He was bad-tempered, controlling and involved in a fair share of illegal activities, but he loved his son and was genuinelly mentally ill, and had no idea that too much stress turned him into a crazed psychopathic Mad Bomber supervillain. His modern version is not actually Alternate Character Interpretation but Character Development- Osborn now remembers everything he did as the Goblin and had gotten his mental issues under a certain level of control; its just, he decided that he liked being an evil, remorseless megalomaniac, and now just has more control over himself. This development occured when he came Back from the Dead in 1996- the animated series predated that development, while the Raimi series only came shortly after it (and Raimi seems to prefer Silver Age stories anyway). Almost every other version after these have gone with making Osborn the Complete Monster we all know and fear today, and Osborn has become a much more prominent villain in the wider Marvel Universe as a direct result of this characterization (though he is still three-dimensional and retains some tragic elements).
Complete Monster: Following his resurrection in the nineties. Once a Tragic Villain who suffered from a Split Personality that forced him to become the Green Goblin, Norman was apparently slain after he threw Spider-Man's girlfriend, Gwen Stacyoff a bridge, in what many fans saw as his Moral Event Horizon. Brought Back from the Dead in the nineties, Norman revealed that he had been the mastermind behind the Clone Saga, buried Aunt May alive and killed Peter's clone, Ben Reilly, while gloating that he could now remember all the crimes he'd committed as the Goblin and was proud of them. Since then, he has gone on to be a major player in the Marvelverse, masterminding the creation of the Dark Avengers. During this time period, he kept the Sentry in line via drug addiction (then had his wife killed), planned to have the caputred Songbird decapitated (so that he could mount her head on the wall and masturbate to it), and deliberately triggered a war with Asgard by having the U-Foes attack Agardian warrior Volstaag in a football stadium, resulting in thousands of casualties. During this time, he also seduced and impregnated his son Harry's girlfriend, then plotted to have Harry killed, because he thought Harry's tragic death would earn him public sympathy. These, by the way, are all actions committed by the Norman Osborn persona; the Green Goblin persona remains an Axe CrazyMad Bomber who regularly endangers/kills hundreds of civillians during his battles with Spider-Man, and, in commemoration of Gwen Stacy's death, tried to recreate the tragedy with Mary-Jane Watson, Peter's then Love Interest, as the victim. As Norman Osborn he's a cold-blooded, calculatingpsychopath who treats everyone as a means to an end. As the Green Goblin he's a violent lunatic who threatens every person in the vicinity.
Magnificent Bastard: Sometimes portrayed this way, particularly in The Spectacular Spider-Man TV series which was written by Greg Weisman, the same guy who wrote David Xanatos.
Moral Event Horizon: The murder of Gwen Stacy is almost universally agreed to be when Norman crossed it, and perhaps the second most infamous murder in Spidey's history (following Uncle Ben's demise). It was extremely jarring to readers at the time because it was the permanent deathof a main character.
Though if you want to get technical, since he was still very much in Ax-Crazy mode and it wasn't really any worse than what the Goblin tried to do on a regular basis, Norman could still be excused for it. The Moral Event Horizon for the character probably occurred shortly after that, when he woke up in the morgue for the first time with a measure of sanity- and promptly murdered some vagrant who looked like him and put his corpse in his coffin. Or when he went to Europe and set up/ joined a major crime syndicate and immediately started using it to create the Clone Saga, just to mess with Spidey and possibly as an elaborate plot to destroy Marvel Comics as an industry.
Newer Than They Think: Thematic example. In Revenge of the Green Goblin Osborn, his son Harry then long dead, started to realize that Peter himself was everything he ever wanted in a son and heir- smart, resourceful, tough, and able to live through everything life throws at him. This was since retconned out of existence (partly because Harry is back, partly because Norman no longer knows who Spidey is), but it was well received and became an integral part of his character in other media, such as the movie and the Spectacular Spider-Man cartoon. Even Ultimate Spider-Man uses it to great effect (and when Norman's around, the series reallyforgets it's a comedy.) So successful some more recent fans thought it was always an integral part of the character.
It just works so well when Harry is still around. Adds to Harry's angst and friction with Peter, and Norman's evilness.