One of many classes in MMORPG game called: "Lineage2"
It is class specified to ORC race. In many oppinions it's one of the best support classes in the game. Overlord is sometimes called OL for a short. OL can evoluate into Dominator. Overlord has got mass skills called seals it can debuuff numerous number of mobs or even other players.
"Oh dude you 0wned me with your OL!!!!111"