An alliance is an agreement or treaty between two or more groups. These are usually political agreements, often made to advance of common goals or interests, such as to defend territory in military situations or merely for trade benefits.
Some examples of political alliances include:
- A nation-state on an planet encountered by Enterprise NX-01 in 2152. (ENT: "The Communicator")
- A cadre on Turkana IV known as the Alliance. (TNG: "Legacy")
- The European Alliance on Earth, a nation-state. (TNG: "Up The Long Ladder")
- Klingon-Cardassian Alliance, the dominant 24th century military power in the mirror universe Alpha Quadrant. (DS9: "Crossover")
- The Bajoran Alliance for Global Unity. (DS9: "The Siege")
- The Nyberrite Alliance, an interstellar power located on the edge of Federation space. (DS9: "The Way of the Warrior")
In addition, a number of military alliances were formed, including:
- In an alternate timeline, the Na'kuhl forged an alliance with the Nazis during World War II. (ENT: "Storm Front")
- A pre-Federation military alliance to stop a common threat to several species in 2154. (ENT: "United")
- An Earth/Andorian/Vulcan/Tellarite alliance formed by 2160 which defeated the Romulan Empire in the Romulan Wars. (ENT: "In a Mirror, Darkly, Part II")
- The Federation Alliance, the forces allied against the Dominion during the Dominion War. (DS9: "Tears of the Prophets")
- Kathryn Janeway forged a temporary alliance with the Borg in early 2374. (VOY: "Scorpion, Part II")
- The Dominion-Breen Alliance of 2375. (DS9: "'Til Death Do Us Part", "Strange Bedfellows", "The Changing Face of Evil")
- The Alliance was the name given to the combined forces of four ships that pooled their resources to escape a subspace anomaly in the Delta Quadrant known as "The Void". The Alliance included a Nygean ship, a Hierarchy scout ship, an unnamed vessel and the USS Voyager. (VOY: "The Void")