As Marvel Comics’ flagship hero, the alter ego of Peter Parker has one of the best rogue’s galleries in comic book history.
Many debates have been had over which enemy of Spider-Man can truly be called his nemesis. Good points have been made in favor of Otto Octavius (Dr. Octopus), Norman Osborn (Green Goblin), Eddie Brock (Venom), Cletus Kasady (Carnage) and even J. Jonah Jameson.
However, Spider-Man’s nemesis, his greatest enemy, is Peter Parker.
The Origin

The conflict between Peter Parker and Spider-Man began with the incident that causes Spider-Man to be a hero, the death of Ben Parker.
It can be argued that Peter Parker made the decision that ultimately led to the death of his uncle but the truth of the matter is simple: Spider-Man let a thief go and Peter Parker lost his uncle.
The guilt forces Spider-Man to use his powers to selflessly help others because of the one person he failed at the very beginning, Peter Parker.
And their conflict only worsens from that moment.
A Conflict of Responsibility

“With great power comes great responsibility” is not just a catchy and meaningful motto but it is at the very heart of the conflict between Spider-Man and Peter Parker.
Spider-Man does his best to fight crime in New York as it is his sworn responsibility, a duty he shoulders along with his power. Fighting crime, catching villains and protecting the innocent is what Spider-Man does and he does it well.
However, Peter Parker also has responsibilities. As a nephew in a financially struggling family, he has to help with the bills of the household or Aunt May might lose the house with all the cherished memories she has of Ben Parker. As a student, he has a responsibility to attend classes, do classwork and homework, get good grades and graduate. As an employee, he has a responsibility to do his job well so he can support his aunt financially.
These two disparate lives clash viciously and often as Spider-Man and Peter Parker wrestle with each other over whose responsibilities must be prioritized and whose must wait.
When Spider-Man wins, Peter Parker’s personal life suffers. His grades go down, his friends lose faith in him and his aunt worries about his erratic behavior. Ironically, Peter’s employment as a photographer of Spider-Man’s crime fighting is usually the only part of his personal life that doesn’t suffer but it creates a whole new complication for Spider-Man.
When Peter Parker is prioritized over Spider-Man, criminals escape, innocent lives are put in danger and public trust in Spider-Man goes down. That makes crime fighting even harder for Spider-Man. Even at a time when Peter Parker is doing well by taking pictures for the Daily Bugle, those pictures are used to persecute Spider-Man by creating false narratives around his activities (comics did fake news before it was a thing).
The best stories about the webslinger are always about how Peter Parker and Spider-Man clash in this way. A perfect example is Sam Raimi’s Spider-Man 2 which showed the conflict get so bad Spider-Man began to lose his powers.
A Conflict of Identity

The conflict between the two personalities extends into a more personal space, identity. There is a constant wrestle between Spider-Man and Peter Parker with regards to character as they are a foil of the other.
Spider-Man is outgoing, exuberant and prone to making jokes at inopportune times. Peter Parker is socially awkward, neurotic and more withdrawn. They share a few traits in common but for the most part, Peter and Spider-Man are two disparate entities that share a single existence.
As a result, Peter Parker and Spider-Man do not share the same values. Issues that draw sympathy from Peter Parker must be approached differently for Spider-Man. The lawful hero and the sympathetic person encounter various situations where the two diverge on how they respond.
An example is the comic book storyline that featured student demonstrations in Empire State University, Peter’s university, that was a reflection of the real-world situation in Columbia University. Peter Parker as a student was sympathetic towards his fellow students and felt obliged to stand with them. Spider-Man, as a protector of law and order, was faced with stopping violent protests that endangered lives and destroyed properties.
The Irony of the Conflict

As much as it seems that Peter Parker and Spider-Man would both be better off without each other, the truth is they are strongest when the two personalities move in unison.
Despite all the clashes with their disparate identities and responsibilities, Spider-Man is at his strongest when he pursues a course of action that Peter Parker wholeheartedly agrees with.
One of Spider-Man’s most noteworthy comic book moments comes when he battles Dr. Octopus for a cure that will save Aunt May from certain death. During the course of the battle, the underwater lair collapses on Spider-Man as Octavius makes his escape. With the weight of a building on his back and the water rising to drown him, Spider-Man finds the strength to lift the entire building off himself and escapes Dr. Octavius’s lair to deliver the cure to Peter’s aunt.
A more recent example can be found in the latest movie from the MCU; Spider-Man Far From Home. When Mysterio (Quentin Beck) threatens to use Tony Stark’s technology to endanger lives and kill Peter’s friends, Spider-Man is finally able to properly utilize his spider-sense to see through Mysterio’s illusions and shut down his drones.
Conclusion

Spider-Man and Peter Parker may directly oppose each other a majority of the time but, despite their conflict, the unified front they present when necessary is nigh invincible.