A blacklist is a list of players that has been made by a specific person or guild whom have listed other specific players to be avoided in groups, raids, etc for:
- Kill Stealing
- Ninja Looting
- Spamming
This has proven to be a very ineffective way of dealing with "Bad" players due to the sheer volume of players and different guilds on one realm along with the extremely notorious players always having the option to change their name, leaving an effective "Blacklist" up to a future implementation only possible by Blizzard.