Triad

A Triad was a ruling trio of Silurians. Although a Triad was purportedly in charge of the whole of the Silurian race, other Triads could rule smaller groups.

History
One Triad were the "custodians" of the Silurian race. In one account, Icthar told Sauvix of Elite Group One that he was the "sole survivor of the Silurian Triad", with Scibus and Tarpok being Icthar's "companions". (TV: Warriors of the Deep) According to another account, Icthar told the Third Doctor that he was the leader of the Triad, with Scibus as Icthar's Second, and Tarpok his Science Adviser. (PROSE: The Scales of Injustice)

Another Triad, made up of Silurians of the same subspecies as Vastra's, were in charge of a hibernation facility located below London. They were briefly released in the 1890s and tried to use their Tyrannosaurus rex, as well as the Silurian plague, to cleanse their "zone" of human presence. When they learned that Vastra's colony had been wiped out save for her, they also claimed authority over their "zone". Vastra eventually knocked them out and re-entombed them in their hibernation facility. (GAME: Lost in Time)

In the 2010s, Kate and Osgood tried to invoke the Triad when negotiating with Grand Marshall Jastrok. He viewed the Triad with contempt as being 'peacetime' leaders. (AUDIO: Call to Arms)

In 2085, a new Triad was in place when the Seventh Doctor came to negotiate with them. (AUDIO: The Silurian Candidate)