Mary Sue

A Mary Sue is a type of character in a work of fanfiction. Often the idealized self-insert of the writers (known as Suethors), Mary Sues are considered by their creators to be perfect in every way. Common traits of Mary Sues include

•oddly colored eyes or hair •bizarre names •connections to Canon characters, either family or romantic

The true indication of a Mary Sue, however, is if they change the focus of the canon to revolve around them. A Mary Sue is always a sign of bad writing.

The male version of a Mary Sue is called a Gary Stu or a Marty Sam.