The USS Illustrious (NCC-1863) was a Surya-class frigate, then an Avenger-class heavy frigate, active in the 23rd century. (Ships of the Star Fleet, vol. 1 [revised])
Illustrious was commissioned in April 2252. During the Four Years War, the ship was assigned to Task Force Constitution, under the overall command of Garth of Izar. (Star Trek: Avenger: Early History of the USS Avenger)
Illustrious was refitted to Avenger-class standards and recommissioned in early 2278. (Ships of the Star Fleet) Her commanding officer in the mid- to late-2280s was Carson J. Hardacre.
- In Orion Press continuity, NCC-1863 was assigned to a Miranda-class frigate, the USS Challenger. (Orion Press: "The Cost of Freedom", "Never Forget", "Return to Xantharus")