The Remans are the main antagonistic faction of the film Star Trek: Nemesis. The film remains their only on-screen appearance.
The Remans were used as a slave race by the Romulans from the neighbouring planet. They mined their planet's minerals and were used as cannon fodder by the military. Their fortunes began to change however when Shinzon, a human clone of Captain Picard created by the Romulans for an aborted plan, was exiled to Remus. He became their leader and began a campaign for Reman supremacy against both the Romulans and the Federation.
Shinzon managed to convince a cabal of warlike Romulans to assist him and together they assassinated the Romulan senate and installed Shinzon as praetor. He quickly elevated the Remans to the position of his personal shock troops and made his former guardian his new Viceroy. His ultimate aim was to use his massive warbird, the Scimitar, to trigger a thalaron cascade that would wipe out all life on Earth.
After Captain Picard escaped from a Reman trap, Shinzon and the Remans took the Scimitar on a course to Earth and ambushed the Enterprise in the Bassen Rift, where they were unable to call for help. However, Shinzon's Romulan allies had begun to realise the Remans did not have their best interests at heart and came to assist the Enterprise. Although the Romulan ships were quickly destroyed or disbled, they managed to inflict damage on the Scimitar. The Enterprise then rammed the Reman ship, crippling both vessels.
Remans boarded the Enterprise but were fought off by Commander Riker and Lieutenant Commander Worf. Shinzon attempted to use the thalaron cascade to kill everyone on the Enterprise but Lieutenant Commander Data blew up the thalaron generator in an act of self-sacrifice, destroying the Scimitar and killing any Remans who remained on board.
The existence of Romulus' twin planet Remus was established in the episode which introduced the Romulans, "Balance of Terror". However, there was no mention of its native species until the film Star Trek: Nemesis.