USS Orion was named as the former posting of the Satarran agent posing as Kieran MacDuff on his falsified personnel file. According to that file, he was one of the ship's operations managers. (TNG-R: "Conundrum")

This starship was only mentioned in writing.
According to apocryphal sources, there were two actual 24th century Federation starships operated by Starfleet, named Orion. According to the FASA source book Star Trek: The Next Generation Officer's Manual, there was a Constellation-class USS Orion (β). According to Star Trek: Starfleet Corps of Engineers eBooks Wildfire, Book 1 and Wildfire, Book 2, there was also a Steamrunner-class USS Orion (β).