The Romulan battlecruiser was a type of starship, a battlecruiser used by the Romulan Star Empire in the 24th century. Several ships of this design were detected near Federation outposts in the year 2364. Starfleet starships were diverted to the edge of the Romulans' territory as a show of force, a precaution against an expected attack. Data was able to calculate the time it would take for the detected battlecruisers to reach the outposts and effect an attack. (TNG episode: "Angel One")