In StarCraft, the Xel’Naga are the ancient beings who created the Protoss and the Zerg.
The Xel’Naga are an advanced, spacefaring species devoted to guiding the evolution of life. Their experiments produce the Protoss, associated with purity of form, and the Zerg, associated with purity of essence. This concept becomes one of the central mythological foundations of StarCraft.
The original game reveals little about the Xel’Naga compared with later installments. StarCraft II expands their history and introduces Amon, a Xel’Naga whose actions drive major events in the trilogy.
The Xel’Naga should not be confused with the Overmind, which is a Zerg intelligence, or the Conclave, which is a Protoss governing body. The Nerazim are a Protoss faction descended from the wider Protoss civilization, not creators of either species.