self-insert

To insert oneself.

Noun

A character in a story who represents the author's own person.
- [Joss Whedon] loves sexualizing her, like […] making her fall for his self-insert Bruce Banner. - 2018 July 13, Kate Gardner, “HBO Greenlights a New Joss Whedon Show, Critics Immediately Groan”, in The Mary Sue:
A character in a story who the reader/viewer is meant to identify with.
- The female character has to be likable. She's a self-insert for the female viewers so she probably won't be unique, but watching her interact with other characters can't be frustrating. - 2015 October 7, Lynzee...
An original character created by a fan to represent how they imagine themselves in a particular fictional universe.

From self- + insert.

To insert oneself.
- For centuries, the commonest forms of implant had either been grown in situ or were designed to self-insert painlessly via existing orifices […] - 2000, Alastair Reynolds, Revelation Space:
To insert something into one's own body.
- In Oregon, a group called Ceek Women's Health has begun clinical trials for a series of new devices—including […] a speculum that patients can self-insert. - 2018 October 5, Arielle Pardes, “The Speculum Finally Gets a...
To insert one's own person into a story as a character.
- The character looks like Goldman and is voiced by him, so critics said he was self-inserting himself into a romantic situation with an underage character. - 2017 June 1, Beth Elderkin, “This Creepy Powerpuff Girls...