grefer

A total asshat Who has no other purpose in life, then killing you and destroying your shit. The term started in Minecraft, but quickly went into other games.

Games were Griefers run rampant are as followed
GtaV
Rust
Minecraft however, not very common anymore
Grefer:* kills you in game*
Victim:* Punishes griefer*
Grefers parents: *wonders where they went wrong*