A damage dealer, also called DPSer, specializes in causing severe amounts of damage, at the expense of general utility. Most pick-up groups will advertise for damage dealers when forming, as in "Group needs two healers and a damage dealer!". In PvE, necromancers and elementalists are prime candidates for damage dealing and are often also called nuker as they usually deal large amounts of damage in an area. PvE damage dealers are usually relatively inflexible and fragile, due to the high energy cost of their skills and their lack of self-healing; thus, damage dealers usually sit in the backline of a party, so they can avoid taking damage themselves.
In PvP, damage dealers are often warriors, though theoretically any profession can take up on the role depending on the team composition. Damage dealers in PvP rarely nuke; they concentrate on spikes to take out enemies faster than their monks can heal them.