From Diablo Wiki
They are Beasts.
Moon Clan Spearthrower, but it's all but certain there will be a variety of different goat clans in Diablo III, as there were in the earlier games in the series.
Though Goatmen were a popular monster in Diablo 1 and Diablo 2, the Goatman Spearman is a relatively new unit, as there previously have been Goatman Archers. It's possible that they either put down their bows for more powerful ranged weapons, or simply added to their range of weaponry. In either way, it's pretty straight-forward to understand what they do, they throw spears to support regular Goatmen.
Seeing as how the AI for the Goatman Shaman is relatively bright, we can likely expect these spear-throwers to run away when attacked in melee range, and start throwing more spears when outside of danger, preferably behind other Goatmen.
Spearthrowing Goatmen look very much like regular ones, as shown in the image to the left here.
Spells and Abilities
There are no known spells or abilities by the Goatman Spearthrower.
Known Khazra Clans
- Moon Clan
- Night Clan (unconfirmed in D3)
- Blood Clan (unconfirmed in D3)
- Death Clan (unconfirmed in D3)
- Hell Clan (unconfirmed in D3)
The Goatman Spearthrower share the background story of the other Goatmen.
Diablo I Monster
There are Goatman Archers in Diablo I, which are basically just a Goatman with a bow and arrow instead of an Axe.
Diablo II Monster
You can find pictures in the Diablo 3 screenshot and picture gallery: