This mod adds a command that allows you to change the display name of a player.

/quicknick "Bob"

Formatted text is also supported!

/quicknick {"text": "Bob", "color": "blue"}

Includes config to change the permission level for the command, default is permission level 1. Only needs to be installed on the server for death messages and chat, client if you want nametag and player list.

Project no longer being worked on. Source available here: https://github.com/HecknTarnation/QuickNick

Feel free to edit and modify the code (along with publishing your modifications.)