A flagship is a term referring to the status conferred upon a starship.
Typically, a flagship is a vessel commanded by a flag officer (an admiral or similar rank).
In an alternate timeline, Admiral Riker spared the Enterprise-D from decomissioning by making her his personal flagship.
In 2373, Admiral Hayes led the Federation fleet against a Borg cube at the Battle of Sector 001 aboard his flagship. (Star Trek: First Contact)
The term also properly applies to the ship of whatever commanding officer is in charge of a grouping of ships. Both the USS Defiant, and the USS Voyager acted as flagships at one point or another during their service lives, though neither was formally referred to as such. (TNG: "Redemption II";DS9: "The Way of the Warrior", "Favor the Bold", "Sacrifice of Angels";VOY: "Equinox")
A third, more colloquial usage of the term can mean that the ship in question is considered an "exemplar" of the best capabilities and virtues of the force it represents.
Known flagships
First Federation
Federation Starfleet
- USS Defiant
- USS Enterprise (NCC-1701-D) (destroyed 2371)
- USS Voyager
Klingon Empire
- IKS Kronos One
- IKS Bortas (Vor'cha-class)
- IKS Negh'Var
- IKS Rotarran (Martok's flagship)
- ShiVang's flagship
Romulan Star Empire
- Praetor's flagship (destroyed 2266)
- Lovok's Warbird (destroyed 2371)
- IRW D'ridthau (destroyed 2375)