So you're scratching your head and wondering who the heck Mary Sue IS, hm? Well, "Mary Sue" is an unkind term used to describe a certain kind of character, a style of writing. She (or he) is created to serve one purpose: wish fulfilment. When a writer invents someone through whom he/she can have fantastic adventures and meet famous people (fictional or real), this character is a Mary Sue or Gary Stu.

Mary Sue is any original or deeply altered character who represents a slice of his/her creator's own ego; s/he is treasured by his/her creator but only rarely by anyone else. More negatively, a Mary Sue is a primadonna (usually but not always badly-written) who saps life and realism out of every other character around, taking over the plot and bending canon to serve his/her selfish purposes.

However, to be fair, even the most trite Mary Sue serves a psychological purpose for his or her creator...and sometimes, believe it or not, the best can wind up being lauded as legitimate characters and gathering fans beyond their original scope. You never know... Which is why I've created this page.

((Compliments of http://www.subreality.com/marysue/explain.htm))