NegaScott

NegaScott, also known as Nega Scott, is Scott Pilgrim's alter ego and dark side, and represents his forgotten past mistakes. He has no lines, and has only appeared in some panels of the comic. NegaScott is the manifestation of all of Scott's callousness, spite, faults, and flaws, and rather than accepting them and himself, he runs from them, thus creating this physical persona. Though NegaScott doesn't appear that often in the series, he can be considered a major character because of what he represents.

Histroy
NegaScott is first seen in Scott Pilgrim Gets it Together after Scott first contracts The Glow, after discovering that Roxie Richter spent the night at Ramona Flowers's apartment. Scott, however, refuses to accept NegaScott and charges through him, causing him to disappear.

NegaScott has a short appearance in Scott Pilgrim vs. the Universe, after Ramona leaves and Scott is staying with Stephen. Scott is brushing his teeth and he looks in the mirror, half of the mirror is him while the other half is NegaScott.

NegaScott is seen again in Scott Pilgrim's Finest Hour, when Scott on his "wilderness sabbatical" and contracts the Glow the second time, Scott tries to defeat NegaScott, believing it to be the only way to get over Ramona and carry on with his life. Kim Pine, however points out that if Scott forgets his past mistakes, he won't be able to learn from and he'll just keep making the same mistakes over and over again. Scott then sees a vision of Ramona, causing him and NegaScott to stop fighting. Then, NegaScott merges with him, allowing Scott to finally accept his faults and remember all his past memories he had previously forgotten.

In vs. the World
In the movie, Nega Scott appears shortly after Gideon was defeated, which the dying villain implies may be a creation of his own doing. Knives and Ramona go outside as Scott says he needs to face this challenge himself. In a hilarious anticlimax, both Scott and Nega Scott emerge from Chaos Theatre a few minutes later talking and laughing. When asked what happened, Scott says they just "shot a shit," that Nega Scott was a great guy, that they had "a lot in common" and they were gonna do brunch sometime later that week.

Nega Scott's appearance in the movie is foreshadowed by the game Scott and Knives play, Ninja Ninja Revolution, in which Scott enters a solo round where he has to face a Nega Ninja, Scott mentions he could never defeat the character as his character is effortlessly defeated. There are also at least two deleted scenes of Scott having visions of Nega Scott. The first time was after seeing Knives and Young Neil together. While washing his hands in the restroom, he looked into a mirror and saw Nega Scott next to him. When he turned around, Nega Scott was gone. The second time is at the "4" club, right before he fights Roxie. While arguing with Ramona, he looks up and sees Nega Scott scowling at him, in which he tells Ramona that he's sorry and that he's not normally like a total ass.

Though mostly intended to be humorous, the twist at the end involving Scott and Nega Scott becoming friends instead of fighting can be interpreted as Scott being able to accept his faults.