Icthar

Icthar was the leader of the Silurian Triad. (PROSE: The Scales of Injustice)

According to 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)

When Icthar had awoken in a world dominated by humans, he had made contact with a shelter beneath the island of L'Ithe. Following the death of the shelter leader Daurrix, Icthar made Chukk, who had already been a favourite of Icthar's, this shelter's leader. The Third Doctor pleaded with the Triad to seek peace with the human race, but this failed after a C19 operative killed Chukk. (PROSE: The Scales of Injustice)

The Fifth Doctor believed he had been killed, but he had not. Later, in 2084, Icthar decided, with Scibus and Tarpok, to take over Sea Base 4 with Sea Devil troops and a Myrka, and trigger a nuclear war between two human factions. After recovering from hexachromite gas poisoning, Icthar shot and killed Commander Vorshak with a Sea Devil weapon. Turlough then forced the weapon from Icthar, and killed him with it. (TV: Warriors of the Deep)

In an alternate reality where the Silurians retook the Earth, Icthar was a member of the Council for Operations. Unlike Morka, who expressed regret for killing the Doctor, Icthar remained hostile to human threats and responded to them with excessive violence. (PROSE: Blood Heat)

Behind the scenes

 * The Target novelisation of Doctor Who and the Silurians, Doctor Who and the Cave-Monsters, does not name the scientist, Old Silurian or Young Silurian as "Icthar", but respectively as K'to, Okdel and Morka.
 * Additionally, Icthar appears in the novel The Scales of Injustice, which also establishes that Silurians belong to different races or sub-species, with Icthar belonging to a different sub-species than the one seen in Doctor Who and the Silurians. Just as in Doctor Who and the Cave-Monsters, the novel also identifies K'to as the "Silurian Scientist."