In the rich text editor:
@carrionmouth
In a comment:
[carrionmouth](https://chowlings.com/user/carrionmouth)
For Names and Avatars:
In the rich text editor:
%carrionmouth
In a comment:
[![carrionmouth's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/carrionmouth) [carrionmouth](https://chowlings.com/user/carrionmouth)