Jaron

From Memory Alpha, the free Star Trek reference.

Jaron was a Romulan living on Romulus during the 2360s. In 2368 he was a member of Spock's underground Vulcan-Romulan reunification movement.

When Jean-Luc Picard and Data visited Romulus that year to search for Spock, Jaron posted as a soldier from the Romulan Guard who observed the two disguised Starfleet officers as they ate soup in a Krocton Segment cafe. When Picard and Data attempted to leave the establishment, Jaron and a second soldier stopped the two, and led them Senator Pardek, who informed them not to let his "soldiers" alarm them, as they were simply trying to get them off the streets to the underground's hidden cave system. (TNG: "Unification I")

He would learn about the similarities between the two races, and the need for Romulans to abandon their plans of conquest and embrace logic instead. After Spock helped foil a Romulan plot to conquer Vulcan, he remained on Romulus to teach Jaron and the rest of the underground movement. (TNG: "Unification II")

Jaron was played by Daniel Roebuck. In the scripts he was referenced as "Romulan #1".