The protoss, a.k.a. the Firstborn, are a sapient humanoid race native to Aiur. Their advanced technology complements and enhances their psionic mastery.
The main protoss cultural groups are the Khalai, who adhere to the communal Khala, and the Nerazim, who reject the Khala. In addition, another branch of the protoss separate from the Khala called the Tal'darim lives in various places in the galaxy.
Protoss civilization was reunified when the Khalai and Nerazim, sundered since the Discord, were reunited after the devastation of Aiur by the zerg during the Great War.
Alongside the zerg and terrans, the protoss stand as one of the three dominant species of the Milky Way. Protoss are not found outside the Koprulu sector.