Icthar

Icthar was one of a Triad of Silurian leaders.

Following his revival into a world dominated by humans, Icthar decided, with his fellows, to take over Sea Base 4 with Sea Devil troops and a Myrka, and trigger a nuclear war between two human factions. His familiarity with the Doctor suggests an earlier encounter. Turlough shot him with a Sea Devil weapon while he was recovering from hexachromite gas poisoning, he attacked and killed Vorshak as his last act. (DW: Warriors of the Deep)

Behind the scenes

 * Some fans commonly associate Icthar with the surviving member of the three Silurian leaders, "Silurian Scientist" seen in Doctor Who and the Silurians.
 * The Target novelisation, Doctor Who and the Cave-Monsters gives alternative names of all three and does not list Ichtar as one of the three.
 * Additionally, Icthar appears in the novel MA: 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.