Star Trek: 12 Most Powerful Beings Ever
8. Pah-Wraiths
The Pah-Wraiths are the devils and demons of Bajoran theology, trapped in the Fire Caves on Bajor itself. Despite this, they still managed to cause havok in the years leading up to Gul Dukat's attempted releasing of them.
The first Pah-Wraith to appear took possession of Keiko O'Brien, who had visited the Fire Caves. It returned to the station and blackmailed Miles into constructing a weapon that would destroy the Prophets in the Wormhole. On this occasion however, he was able to outsmart the being and save his wife.
Things kicked into a higher gear with Sisko's discovery of the ancient city of Bahala. Here, a tablet was located describing the Reckoning, the final battle between good and evil. The Pah-Wraith contained within was freed when Sisko smashed the tablet, though was banished by Kai Winn, who interfered and delayed the battle.
Dukat would then become an acolyte, causing the death of Jadzia Dax while possessed, further causing the Prophets to engage in battle with the Pah-Wraith and cut themselves off from Bajor.
Though it would eventually cost the lives of Winn, Dukat and, potentially, Sisko, the Pah-Wraiths were finally and permanently sealed within the Fire Caves after the destruction of the Test of the Kosst Amojan.