A Canon Sue is a MarySue who happens to be a [[{{Canon}} canonical]] character. This could be one of two things:

# A PossessionSue. It's more frequently referred to as Canon Sue, but it has its own article.
# A professional work in which a canonical character already has the attributes of a MarySue.

In the second version, this can sometimes be tricky to identify; creators often draw on their own personality, appearance, and/or history for inspiration, since it's easy and convenient to write [[WriteWhatYouKnow what]] and [[WriteWhoYouKnow who]] you know, so the appearance of these doesn't automatically mean a Canon Sue. However, if the character that appears is very obviously an AuthorStandIn, especially to such a degree that the character's back-story and the author's biography are practically interchangeable; [[AuthorTract believes in everything the creator believes]] and does everything the creator does ([[WishFulfillment or wants to do]]) and is absolutely correct and perfect in both; is over-idealized and perfect to a fault; is disliked or disagreed with only by characters who are clearly shown to be stupid, mad, or evil; and/or (most importantly and required) gives the impression that the story exists only to further them and them alone, ([[WeAreTeamCannonFodder most often to the detriment of any other characters present]], [[CantCatchUp who simply cannot measure up to]] [[CreatorsPet the author's clear favourite]]), you're in MarySue territory.

ShipToShipCombat also plays in, as the Canon Sue accusation is often blatantly leveled at characters just because they hook up with a lead (or the EnsembleDarkhorse) who the accuser ships with somebody else. Also, with the general trend of MarySue being used as an all-encompassing insult for any female character considered to get "above herself", this accusation gets thrown around a lot without much basis in fact.

In general, Canon Sues are significantly less common than {{fanfiction}} Mary Sues, since most professional authors have more skill, talent and accumulated experience than the amateurs who write fanfiction, not to mention the help of professional editors. However, this means that when they do occur they are significantly more visible ([[MyImmortal who's going to remember the hastily typed out daydream of a 12 year old girl in a year?]]). Due to the author creating an entirely different template for the work of fiction, they can set up the rules of TheVerse that allow or disallow particular tropes or characteristics. As such, they can choose what CommonMarySueTraits are allowed, making it a bit harder to see when plot bias is in effect. However, they're hardly immune to this trend. Nor is this a new element; Creator/GeorgeEliot's ''Literature/SillyNovelsByLadyNovelists'' castigates many original novels of her day for obvious Mary Sue traits (among other flaws).

For the most blatant and infamous examples see CreatorsPet. The MagicalGirlfriend, {{Tsundere}} and YamatoNadeshiko, while occasionally possessing similar traits, are not usually viewed as such; they are seen more as targets of enticement instead of ones to emulate; whether they're ''still'' {{Canon Sue}}s is left to the viewer. Also see TheAce, which puts an idealized character in a supporting role in the story, often serving as a rival, a foil, a source of comedy, or as a mentor (or possibly just the HeroOfAnotherStory). SuetifulAllAlong can also play a part as well.

'''No examples, please. This only defines the term.'''