Griefers

A griefer is a player who deliberately irritates and harasses other players, often using aspects of gameplay in unintended ways (or overusing existing game aspects) especially when it involves player killing, but is certainly not limited to just that. A griefer derives pleasure primarily or exclusively from the act of annoying other users, and as such is a particular nuisance, since in-game penalties do not usually deter them.

You can find griefers anywhere. They are mostly opportunists looking for any and every chance to spoil your enjoyment.

Things to remember about griefers

Griefers are fuelled by reaction. If you react to anything they have done it will only add to their fun even more. Do not make yourself a bigger target by insulting griefers, bad-mouthing them, or otherwise. If they think you're an emotional individual who reacts explosively to their actions against you, they might never leave you alone!
You have a REPORT PLAYER function on the main menu. If you feel your enjoyment of the game is being ruined by acts of griefing, report it and the player(s) involved!
Commanders will often accuse other players of griefing, simply because they have been attacked.
A commander who carries out a revenge attack on you and destroys your ship is NOT a griefer!
A pirate is NOT a griefer!
A bounty hunter is NOT a griefer!
A commander who attacks you for any, or no, reason is NOT a griefer (unless the same player does it repeatedly).
A NPC who attacks you repeatedly for no reason is NOT, by definition, a griefer!