Bone golems are potent undead constructs made entirely of bones and are fueled by Ichor of Undeath. They are one of the deadlier types of undead employed by the Scourge.
Their long, scythe-like arms can cleave through the heaviest of armors. Fortunately, despite their strength, they seem to be rather rare.
They also spawned in large numbers and in unlikely places during the Scourge Invasion event, for instance in Silithus.
Notable bone golems
Manual of Monsters
Appendix Three of Manual of Monsters describes a diferent type of Bone golem, however, the validity of the source is disputed.