Dominion renegades

The Dominion Renegades are a group of soldiers that were initially part of the Terran Dominion, but broke off following the Battle of Char, during the Second Great War. They were led by Crown Prince Valerian Mengsk.

After Sarah Kerrigan was deinfested following the battle of Char, Valerian, Jim Raynor, and Matt Horner attempted to take her to a hidden base of the Umojan Protectorate. However, Emperor Arcturus Mengsk only wanted Kerrigan dead and so sent his forces to find her. This had caused a major rift in the Dominion Armed Forces and eventually erupted into a civil war.

They presumably rejoined the Dominion after Arcturus Mengsk was overthrown and Valerian was crowned the new emperor.