For the space station abbreviated as ISS, please see International Space Station.

ISS, short for Imperial Star Ship, was the prefix designation given to space-faring ships in the Terran Empire registry and in the Terran Resistance Forces in the mirror universe. (ENT: "In a Mirror, Darkly, Part II")

The use of ISS as a prefix for Imperial ships was already in use by the 22nd century, where ships of the NX-class were designated with the ISS prefix. (ENT: "In a Mirror, Darkly", "In a Mirror, Darkly, Part II")

• ISS Enterprise NX-01
• ISS Avenger NX-09

The Terran Empire was still using the ISS prefix for starships in the 23rd century. (TOS: "Mirror, Mirror")

• ISS Enterprise NCC-1701

After the fall of the Terran Empire to the Klingon-Cardassian Alliance, the use of the ISS prefix wasn't used on vessels like the Terran raider, but was resumed when the Terran Rebellion built a Defiant-class starship based on specifications "acquired" from the prime universe. (DS9: "Through the Looking Glass", "Shattered Mirror", "The Emperor's New Cloak")

• ISS Defiant NX-74205