Triad

The Triad were the ruling authority of the Silurian people.

One Triad were the "custodians" of the entire Silurian race. One member of this Triad was Icthar, who was the "sole survivor of the Silurian Triad". The Fifth Doctor was uncertain who would replace Icthar if he died. (TV: Warriors of the Deep)

The Silurian city beneath Cwmtaff was ruled by the Triad of the scientist Malohkeh, the leader of the warrior class, Restac, and the elder Eldane. Malohkeh was killed by Restac after she decided to exterminate the humans in the city. Restac was herself poisoned by fumigation gases released by Eldane, who did not wish for the humans to be slaughtered. (TV: Cold Blood)