Self-Insertion

A self-insertion (or self-insert) is a character which is an insertion of the author. Self-insert characters will usually share characteristics with the author.
 * They will usually be similar in age and appearance.
 * Or they will look how the author wishes he or she looked.
 * They will dress in a way similar to the author.
 * They will share hobbies, interests, and political/religious views with the author.

Self-insertions are sometimes associated with Mary Sues. They may not be, but self-insertions can backfire when the author doesn't let anything bad happen to the self-insert character, because "It's them".