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