Romulan Warbirds are starships in the fictional Star Trek universe. During the shows' run, several types of Warbirds were shown. The most common is designated as D'deridex class, and is almost twice as long as a Federation Galaxy-class starship, of which the Enterprise-D from Star Trek: The Next Generation is a member. They have also been classified as 'B-type Warbird'. In the feature film Star Trek: Nemesis, a second type of Warbird was seen, seemingly less advanced and smaller, and also of a different design. In that same movie, the Scimitar, an extremely advanced Romulan ship was also called a Warbird, leading to the belief that many Romulan ships are classified that way. D'deridex class Warbirds are powered by an artificial quantum singularity, or black hole.