The Romulan Fifth Legion was a military unit within the Romulan Star Empire.
By the mid 22nd century, it was under the command of Admiral Valdore after he was released from prison. Centurion Terix was an officer of the Fifth Legion and was dispatched to protect Doctor Ehrehin i'Ramnau tr'Avrak only to discover that he was killed during the assassination attempt. His soldiers were able to apprehend the assassins and recover Ehrehin's assistant Cunaehr. (ENT novel: Kobayashi Maru (novel))