Manathas (aka; Centurion Jenophus) was a Romulan agent who lived in the 24th century. Even though Manathas was an agent, he wasn't a member of the Tal Shiar, and considered himself lucky enough to never have joined them. Manathas was also accomplished at hand-to-hand combat.
In 2348, Manathas was hired to infiltrate the Federation and attended the wedding of Starfleet officers, Beverly Howard and Jack Crusher. Acting as a waiter, he managed to acquire genetic material from Picard and three other Starfleet captains, as part of Praetor Narviat's program of clandestine infiltration of the Federation.