Mary Sue - There once was a fanfic writer named Mary Sue, who put herself
into her stories (mostly Star Trek, IIRC). She saved the day, won the hearts
of hunky characters from the setting, and was generally all-around perfect.
When Self-Insertion goes too far, it is called Mary Sue-ism. To be a true
Mary Sue, it's not enough to make your Self-Insertion character godlike,
though. The following elements are pretty much de riguer:
If, by the time you've been writing a while, you're not the God-King (or
God-Queen) of the entire setting with a harem of every canon character you've
ever taken a fancy to, you're not doing Mary Sue right.
- You are an idealized version of yourself.
- Everyone in the story comes to realize you are so much better than they
- Anyone you find attractive ends up in bed with you, even if they would
normally be uninterested for whatever reason (being in a committed
relationship with someone else, not being interested in your gender, etc).
- If the stories go on for any significant amount of time, you rise in rank
and power more rapidly than anyone in the setting ever has.
Note: if you do all of these things, but using a canon character or one that
is otherwise clearly not meant to be the author, it's called Marissa
Syndrome, after a long series of Trekfics in which a child on the Enterprise
(I forget which ep she was in) ends up commanding a starship and being ruler
of a planet before hitting 18.