Dark Demon

From Diablo Wiki

Dark Demons are demons. These odd, half-skeletal creatures are summoned from raw, red manhole-like openings in the ground by Dark Cultists.

They are quadrupedal, and look a bit like a dog crossed with a crocodile, then turned inside out. They are quick of foot, but appear to possess only melee attacks.

In the debut gameplay trailer, it was narrated that the Demonspawn summoned by Dark Cultists were not easy to kill, even though the Dark Demons were very quickly dispatched. This may indicate that the Dark Demons in the trailer were greatly powered down, or that the player character had already reached a level so high that the power of Dark Demons were insignificant before him. Exactly how difficult it would be to face a Dark Demons is currently unknown.