Bone golems are deadly undead constructs made entirely of bones and fueled by [Ichor of Undeath]. They are one of the deadlier types of undead employed by the Scourge. The Taam rune is often used in their creation.
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.
In the RPG
This section contains information from the Warcraft RPG which is considered non-canon.
Appendix Three of Manual of Monsters describes a diferent type of bone golem, however, the validity of the source is disputed.