Ovu Mobani was a demon whose power was centered within a Nigerian tribal mask. Ovu Mobani (the name means "Evil Eye") had the power to animate the dead, which it could then attract to the mask. When one of these zombies donned the mask, the demon could manifest in the physical world in that zombie's body.
Ovu Mobani's mask was brought to Sunnydale, in the possession of Buffy Summers' mother Joyce. There, the demon summoned an army of undead that overran a welcome-back party celebrating Buffy's return to her home after a summer alone. During the chaos that ensued, Joyce's friend Pat was killed and arose as a zombie. Putting the mask on, Ovu Mobani manifested in her body. The demon could now project paralyzing rays from its eyes, but it was also vulnerable in that spot. Buffy battled Ovu Mobani and slew it by driving a spade into its eyes. Pat's corpse was vaporized, as were the other zombies. The mask sank into the ground, but whether it is permanently destroyed is uncertain.