The flagship of the Romulan Star Empire in the 24th century.
The D'deridex-class warbird is the largest and best known Romulan warship of the twenty-fourth century, a huge green vessel with a double-hulled shape that encloses an open space in the middle. It is armed with disruptors and torpedoes and fitted with a cloaking device.
Warbirds first appeared at the end of The Next Generation's first season, when the Romulans broke decades of isolation and confronted the Enterprise-D at the Neutral Zone. Commanders such as Tomalak met Picard in several tense standoffs, and Sela, the daughter of an alternate-timeline Tasha Yar, led Romulan forces that backed the Duras family during the Klingon civil war.
After the death of Senator Vreenak in 2374, the Romulans entered the Dominion War on the side of the Federation and the Klingons. Warbirds fought in the war's later campaigns, including the push into Cardassian territory, and remained the symbol of Romulan power.