The House of Duras was one of the most powerful and corrupt Great Houses in the Klingon Empire whose family, lead by it's leader Duras (son of Ja'rod), was heavily influenced in Klingon politics and considered to be next in line for the position of Chancellor of the Klingon High Council. The Duras family was known for their ruthlessness, deception, and use of dishonorable tactics; most notably conspiring with the Romulans and causing the Khitomer Massacre, and their rivalry with the House of Mogh.
A forefather in this house was Duras, son of Toral. In 2153, he died in battle with Enterprise trying to capture Jonathan Archer at the edge of the Delphic Expanse.
In the 24th century, the House of Duras was engaged in a blood feud with Huraga's house.
In 2346, Ja'rod had betrayed his people to the Romulans, providing them with the codes to lower the defenses protecting the Klingon colony on Khitomer. When evidence of this surfaced in 2366, then-Chancellor K'mpec sought to protect the Empire against a possible civil war by blaming Mogh, the father of Worf. Worf challenged this, but when he learned the truth he agreed to accept discommendation, for the good of the Empire.
With the death of K'mpec in 2367, Ja'rod's son, Duras, sought the leadership of the council, standing against Gowron. When Worf discovered that his mate K'Ehleyr had been murdered by Duras, he immediately transported to Duras' ship and challenged him. Duras proved to be no match for Worf, and was killed, leaving House of Duras without a leader as Duras had no legitimate heir, and Gowron free to take his place as Chancellor.
Several months later Duras' sisters Lursa and B'Etor discovered that Duras had an illegitimate son, Toral. Though only a boy, Toral was made head of House Duras and inherited his father's claim to leadership of the council. The Arbiter of Succession Jean-Luc Picard chose to reject Toral's claim, causing those council members loyal to House Duras to withdraw from the council, plunging the Empire into civil war. With this, Chancellor Gowron restored Worf's good name and his family honor. He gave Toral's life to Worf, but Worf chose to spare the boy, who had merely been used as his aunts' pawn.
Although Toral was technically its leader, effectively the House was being controlled by Lursa and B'Etor, who were in turn working in collusion with the Romulans. Picard was able to prove this and block the Romulan supply convoys aiding the Duras' forces. Support immediately fell away and Gowron's forces stood victorious. The Duras sisters continued to fight a private war against the Empire.
Lursa and B'Etor surfaced once again on Deep Space 9 in 2369, selling bilitrium to Bajoran Kohn-Ma terroristTahna Los in order to fund their continuing efforts to gain control of the Empire. As they had committed no crime against the Bajorans they were allowed to go about their business and were not apprehended.
An attempt on Worf's life in 2370 was suspected to have been the work of the Duras sisters, but this proved not to be the case. At this point Lursa revealed that she was pregnant with another heir to the house Duras.
In 2371, Lursa and B'Etor began working with El-Aurian scientist Dr. Tolian Soran, stealing trilithium from the Romulans in order to assist him in the development of a trilithium-based weapon. They captured Lieutenant Commander Geordi La Forge and used his VISOR to discover the modulation of the USS Enterprise-D's shields. The Enterprise was critically damaged as the Duras' weapons fire passed through its shields, unhindered. Lieutenant Commander Data was able to force the activation of the Duras' Bird-of-Prey's cloaking device. With their shields down, a single photon torpedo was enough to destroy the Duras' ship, killing them in the process. However, the Duras sisters may have gotten the last laugh as the damage they had inflicted to the Enterprise was enough to rupture the magnetic interlocks to the warp core, leading to a warp core breach which completely destroyed the stardrive section of the vessel and crippled the saucer module.
Toral, the son of Duras, was defeated in battle with Worf in 2372 in the Gamma Quadrant, when he assaulted Worf, Dahar master Kor and Jadzia Dax on a planet believed to once have been a stronghold of the Hur'q, ancient raiders who reputedly stole the Sword of Kahless.
In the computer game Star Trek: Armada, Toral returns again to take over the Empire. In the game, he mentions that Worf "lacked the courage" to kill him twice before, referring to both TNG: "Redemption" and DS9: "The Sword of Kahless". In the Klingon campaign later in the game, it is discovered that the Romulans are behind the attempt for the House of Duras to take over the Empire. After they fail, the House retreats to Romulan space, causing Chancellor Martok to declare war on the Romulans. The game's Romulan campaign ends with Admiral Sela using the Borg to destroy the remnants of the House of Duras.