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