House Dagoth was one of the six Dunmer Great Houses of Morrowind. The members of the House were known as brave warriors and powerful enchanters. Voryn Dagoth, the leader of the House, allied himself with the young Nerevar, offering his wisdom, strength, and friendship to the future ruler. Over time, he became Nerevar's senior and most-trusted advisor.
House Dagoth's fall occurred at the Battle of Red Mountain. Extremely loyal to his friend Nerevar, Voryn Dagoth (the future Dagoth Ur) fought beside him within the Dwemer fortress and was ordered to defend the profane tools that caused the Dwemer people to vanish from reality. At the time, Voryn suggested that the tools be destroyed to prevent damage to the Chimer. Nerevar, wounded and forlorn due to the war, rejected the notion and left to confer with his friends Vivec, Almalexia, and Sotha Sil, ordering him to protect them until his return.
After some time, Nerevar decided, along with his council, to confiscate the tools and keep them safe from evil hands, but Dagoth Ur refused to give up the tools, insisting he was ordered by Nerevar not to give them up. The Almsivi, or the Tribunal Temple, states that he had been corrupted by the Heart of Lorkhan, and Nerevar fought Dagoth Ur for possession of the tools and defeated him.
The House was not dead, however - Dagoth Ur and seven of his blood brothers fled deeper into Red Mountain, and the children of his House were adopted by others. Over three millennia, Dagoth Ur and his brothers lay in a state of near-death deep below the Mountain. During this time, Dagoth Ur's mind explored the enchantments of the Profane Tools and their links to the Heart of Lorkhan. When he awoke near the end of the Second Era, little remained of Nerevar's friend as he was, but a creature existed who believed himself to have been betrayed by Nerevar and the Tribunal. These feelings incubated over time, pulling him farther into madness.
Using rituals, Dagoth Ur bound himself and his brothers directly to the Heart of Lorkhan, drawing directly on the immense power it possessed. Dagoth Ur saw this power as the birthright of his people, a divine right stolen long ago. His goal was to spread this gift to the Dunmer and possibly other people of Tamriel. To do so, he created a carrier disease, Corprus. He sent out a call to the remains of House Dagoth, creating Sleepers from those Dunmer whose ancestors had been adopted into other Houses. They soon became Dreamers and joined the Sixth House Cult, where the ultimate glory was to partake of the "Divine Disease" and be changed by Corprus.
It might be safe to say that, with the Heart of Lorkhan being released and the death of Dagoth Ur, House Dagoth was effectively destroyed at the hands of the Nerevarine, who had, in fact, been 'cursed' with the "Divine Disease," becoming immune to virtually all other disease (the only known possible exceptions being vampirism and lycanthropy). With not only the loss of the Heart of Lorkhan, which provided Dagoth Ur and his lieutenants with most of their power, and with the death of its leader, its demise is highly plausible.
The crest of this House is an insect.