The Star Alliance is an alliance between many galactic powers including the Klingon Empire, Romulan Star Empire, Cardassian Empire and United Federation of Planets. (Adventures of STAG)
Organized by Galactic Special Ops, a sub-agency of the Star Triangle Advanced Guard in 2485, this alliance would not have been possible if not for camaraderie generated during the Dominion War. All of these powers signed the Treaty of Unification which brought all of the Alpha Quadrant powers together.
This alliance is governed by the Alliance Council which is a duplicate of the Federation Council, only it controls the Alliance instead of the Federation; and the Alliance Senate which has representatives from each sector under Alliance control. This government is responsible for regulating the Star Alliance Military or SAM as well as settling disputes between members.