The genderneutral Term for a Mary Sue or Gary
Stu, named after the Film Director Rian
Johnson. An idealized and seemingly perfect fictional character. Often, this character is recognized as an authors insert or wish fulfillment.
They can usually perform
better at tasks than should be possible given the amount of training or experience, and usually are able through some means to upstage the main protagonist of an established fictional setting, such as by saving the hero.