In the rich text editor:
@HellsDementedAngel
In a comment:
[HellsDementedAngel](https://www.worldofgaia.org/user/HellsDementedAngel)
For Names and Avatars:
In the rich text editor:
%HellsDementedAngel
In a comment:
[](https://www.worldofgaia.org/user/HellsDementedAngel) [HellsDementedAngel](https://www.worldofgaia.org/user/HellsDementedAngel)