In the rich text editor:
@actuallyabear
In a comment:
[actuallyabear](https://painted-relics.com/user/actuallyabear)
For Names and Avatars:
In the rich text editor:
%actuallyabear
In a comment:
[](https://painted-relics.com/user/actuallyabear) [actuallyabear](https://painted-relics.com/user/actuallyabear)