Marcus Octavius was a Roman soldier who was abducted by the War Lords. However, the War Lords failed to hypnotise him into participating in their simulated version of events, and he fought against them as a member of the resistance.
Zoe Heriot memorised Octavius' name while in the War Lords' HQ and later told Russell his name when they attempted to contact all the resistance groups. Octavius was later returned to his own time by the Time Lords after the War Lords were defeated. (TV: The War Games)