The Romulan Star Empire is a major political entity in the Star Trek universe, known for its secrecy and militaristic culture. It is primarily inhabited by the Romulans, a humanoid species that shares a common ancestry with the Vulcans. The Empire is characterized by its advanced technology, including cloaking devices that allow ships to become invisible. The Romulan Star Empire often engages in espionage and diplomatic maneuvering, maintaining a tense relationship with other powers, particularly the United Federation of Planets. Its capital is located on the planet Romulus, while its twin planet, Remus, is also significant within the Empire.