Prophets

The Prophets, referred to as the Wormhole aliens by non-Bajorans, are a group of non-corporeal aliens that inhabit the Bajoran wormhole.

The Prophets appear as glowing translucent blue lights when in normal space. When they communicate with corporeal beings they often take the form of persons familiar to the being they are communicating with. They can also possess a corporeal body and use it to communicate with others. 

At some point the Prophets ejected other similar entities from the wormhole and imprisoned them within the Fire Caves of Bajor. 

Over a ten thousand year period they sent orbs to Bajor, which led to the creation of a religion that worshipped them. (, et al)

During the Dominion War the Prophets intervened in the conflict by removing 2,800 Jem'Hadar warships that were travelling through the wormhole from the Gamma Quadrant to the Alpha Quadrant to join the war. 

The Prophets' conflict with the Pah-wraiths appeared to come to an end when Benjamin Sisko trapped them in the Five Caves forever.