Arguably, Doctor Octopus' greatest achievement has was taking over Peter Parker's mind. The Superior Spider-Man saw Otto Octavius override Peter's brainwaves and put his own spin on the web-slinger's life. However, this wasn't the first time that Doctor Octopus took advantage of Spider-Man's mind.
This first instance of mind control took place in 1967's Amazing Spider-Man #53, by Stan Lee and John Romita Sr, and Peter Parker deal with its immediate side-effects until 1968's Amazing Spider-Man #58, by Lee and Romita, in one of the wall-crawler's first extended epics. While attending a science exhibition with Gwen Stacy, Peter was unfortunate enough to run into Doctor Octopus. Octavius was attempting to steal a nullifier, a device that could protect against incoming missiles. Spider-Man arrived to stop his foe, preventing Octavius from stealing the nullifier.
Although Doctor Octopus got away, Peter planted a spider-tracer on the villain. Octavius saw the tracer, however, and prepared a trap for Spider-Man. When the wall-crawler arrived at Octavius' headquarters, the place exploded. Meanwhile, Doctor Octopus re-established his new headquarters in an unexpected location: Aunt May's home in Forest Hills.
Spider-Man looked everywhere for Octavius before arriving home to find his arch-foe having tea with Aunt May. Out of fear for May's health, Peter knew he couldn't confront Octavius there. During a scuffle with Doctor Octopus' henchmen, Peter lured May out of the house. With Octavius alone, Spider-Man entered the house to take him down.
Unfortunately, just as Peter was about to defeat Doctor Octopus, May arrived. The sight of these two costumed men in battle sent May into shock, allowing Octavius to escape. May was ultimately alright, but Peter swore vengeance upon Doctor Octopus. Spider-Man hunted Octavius down, while Doctor Octopus stole the nullifier from a military convoy.
Doctor Octopus turned the nullifier into a weapon that could disable any mechanical device, which he used to attack Stark Industries. The web-head showed up to confront Octavius and engaged him in a heated battle. Eventually, Doctor Octopus got the upper hand and hit Peter with the nullifier. As a result, Spider-Man's memories were wiped from his mind.
Taking advantage of this amnesiac web-slinger, Octavius convinced Spider-Man that they were partners in crime. Peter accompanied Doctor Octopus back to his headquarters, although he was still uncertain of their partnership. Indeed, when Octavius told Spider-Man to unmask for him, he refused, thanks to Spider-Man's Spider-Sense.
Still, Spider-Man went to steal the rare Isotope-16 when Octavius told him to, breaking into a secure military facility. Upon his return to Octavius' headquarters, however, Spider-Man turned on his new partner. Even without his memories, Peter knew Octavius was a villain, and the two fought once more. The military, including Colonel John Jameson, followed the wall-crawler and intervened in the battle. After Octavius was defeated, Jameson chose to trust Spider-Man's innocence and let him go.
While Octavius was beaten, Peter still had no idea who he was. To make matters worse, everyone thought that Spider-Man was a criminal. When Harry Osborn found a spider-tracer in Peter's closet, he believed that Spider-Man kidnapped him. J. Jonah Jameson then hired Ka-Zar to defeat Spider-Man in battle. Meanwhile, Peter went around the city, asking everyone from Captain Stacy to J. Jonah Jameson to help him figure out who he was. Before he could get any real answers, however, Ka-Zar attacked.
The two fought all across New York City before landing in Central Park. There, Spider-Man plunged into a body of water, nearly drowning. Fortunately, Ka-Zar saved his opponent. When Peter awoke, it was revealed that the shock of the water jogged his memories, returning Spider-Man to his old self. After a long, drawn-out battle with Doctor Octopus, Peter Parker finally recovered his lost memories.
While this might not be the most famous story in Spider-Man history, it still has the distinction of being one of Marvel's early multi-issue storylines. Beyond that, it set a precedent that Superior Spider-Man picked up on and explored in far more depth over an even longer timeframe, cementing this story's place in the hallowed halls of Marvel history.