Spider-Man has the best rogues’ gallery in comics this side of Batman, but at the core of it lies an intense rivalry that has taken many forms over the years: Spider-Man vs. Doctor Octopus. That’s right, it is Otto Octavius - and not Norman Osborn, the Green Goblin - who is, and always has been, Peter Parker’s greatest enemy.
Having made his debut back in 1963’s Amazing Spider-Man #3, Marvel Comics’ Doctor Octopus has been plaguing the wall crawler for nearly his entire existence, and during that time, he’s done more damage to Spidey than any old Goblin ever could. Doc Ock has slain Parker’s friends, swindled his webslinging identity, and even tried to marry his beloved Aunt May - and he did it all with nothing more than his own wit, ingenuity, and custom-made mechanical arms.
Osborn famously takes a turn as the Marvel Universe’s big bad in Dark Reign, wherein he gains control of S.H.I.E.L.D. and turns it into his own fascistic organization known as H.A.M.M.E.R. Osborn even goes as far as to establish his own team of Dark Avengers, a squad he personally leads while wearing a pilfered Iron Man armor - going by the over-the-top moniker of Iron Patriot.
In the end, however, Osborn is an abject failure as a superhero, which can’t be said about Octavius’s time as the Superior Spider-Man. After taking Parker’s body, Doc Ock sets out to prove himself a better wall crawler - and for a time he is indeed a significantly more effective and efficient, albeit vicious, vigilante. In the end, Octavius cedes control of the body back to Parker in order to save the woman he loves, but that just proves the depth of his character and the superiority of his heroism.
The Red Goblin saga features a truly terrifying combination: Osborn wearing the Carnage symbiote. The titular villain goes on to terrorize Spider-Man and slay Flash Thompson, but in the end he is dominated by the alien costume - to the point that, at the end of it all, Osborn is left asylum-bound and believing himself to be Cletus Kasady, the lunatic serial slayer most commonly associated with the symbiote.
It’s thus fair to say that Octavius’s own experience with a symbiote - in the midst of his run as the Superior Spider-Man - goes significantly better. After taking the Venom suit from Flash Thompson, Octavius becomes the Superior Venom, and manages to keep better control over the alien’s impulses than most. When his methods become even more cruel, however, the Superior Venom draws the attention of the Avengers, who he very nearly defeats single-handedly before giving up the symbiote.
Osborn has a clear and present legacy within the Marvel Universe. He’s inspired countless other Green Goblins - including his own son, Harry - and nearly as many Hobgoblins. He also founded the short-lived Dark Avengers during his Dark Reign.
Octavius, however, is responsible for founding one of the greatest supervillain teams in the history of comic books: the Sinister Six, which made their debut in Amazing Spider-Man Annual #1. The whole idea of combining forces with Spider-Man’s most powerful enemies is entirely Doc Ock’s, and it is he who personally selects the inaugural roster and leads them into conflict. He has since been present on - and often in command of - each subsequent iteration of the squad.
Octavius’s run as the Superior Spider-Man ends with Goblin Nation, in which Osborn figures out that Octavius has taken Spidey’s body and uses that knowledge to take over the entirety of New York City. It’s one of Osborn’s - then going by the Goblin King - greatest accomplishments, and a direct blow against the reputation of Doctor Octopus, but it’s also a feat that Octavius himself has long since bettered.
Before he gets the idea to take Spider-Man’s identity, a terminally ill Doc Ock enacts a simpler plan in Ends of the Earth: he puts technology into orbit that he claims would help take on climate change, and then uses it to hold Earth hostage under threat of frying the entire planet. Ultimately, Spider-Man and a team of Avengers are able to defeat him, but only at the very last minute. For a time, Doctor Octopus effectively ruled the entire globe.