This word is acceptable for play in the UK dictionary that is being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. One who griefs: a player who plays a game primarily to reduce other players’ enjoyment of it.

"A court is clearly going to have to place the SL griefer attacks in the context of SL, and more importantly, when we are talking about the criminal law, the reasonable understanding that the *griefer* had of his/her rights/obligations, etc."

troublemaker    troll    stirrer