The Self Insert

Not to be confused with the general act of self insertion.

An in-universe character who is meant to be the creator inserting themselves in their own fictional world. This character often resembles their real-life counterpart strongly with some aspects that make them who they are: their physical appearance, beliefs, practices, and so on. The Self-Insert might even be the creator directly, sharing the exact name, appearance, and overall characteristics.

There are few differing types of Self-Inserts. The most prominent Self-Insert kind is the Mary Sue, an unrealistically high-tier Ace-like Hero who can always bail their creator's creations (the other characters or the world) out of danger with very little effort, has All The Girls, and is rarely ever seen on their knees before their enemy. This can be a creator's sign of Utter Desperation as their real life might not be nearly as good as they make it in their own work of fiction.