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