Icthar

The Silurian 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. (DW: Warriors of the Deep)

Behind the Scenes

 * While fans commonly associate Icthar with the surviving member of three Silurian leaders, "Silurian Scientist" seen in Doctor Who and the Silurians, the Target novelisation, Doctor Who and the Cave-Monsters gives the actual 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 .