A PKer is someone who hunts less experianced players on internet videogames. PKer's are considered the murderers in the RPG universe. Usually, a PKer will target someone who is grossly lower in level then they are, if it is an RPG that is. PKers have zero remorse for who they kill, and will eliminate one or more of the same players over and over again. In the popular game, Diablo 2
, PKers run rampant in hardcore. There are a few in softcore, but not as many.PKers will get more "pleasure" from killing in HC, due to how once their victim is dead; It stays dead for good. Because of this lovable trait, PKers are rarer in softcore, but still should be looked out for! Pkers will use hacks from time to time to improve their "kill rate". Lagging the game, etc.
Usually a PKer is focused on killing weaker people then him, so it's fairly easy to dispose of one with the conventional means.(i.e killing him.)
Pkers will usually, if alone, leave the game if they are outnumbered, or see that they will lose the fight. Pkers who are also skilled fighters are difficult to find- but still exist nonetheless.