Morka

Morka, along with others of his race, encountered the Doctor at an underground base in Wenley Moor. Stubbornly believing that his own race was superior, he rejected the notion of sharing the Earth with the Humans. He then went behind the back of his leader, Okdel, and released a human prisoner who had contacted a deadly disease engineered by the Silurians. Believing that his leader failed him, he killed him and set about reawakening his species so they could reclaim the Earth once again. After being tricked into going back into hibernation again, Morka opted to stay behind when there were only a few pods left, willingly giving leadership of the Silurian race to K'to, the Silurian scientist that helped him. Angry that the Doctor tricked him, he tried to kill the Doctor when he returned to the Silurian base, but he was wounded by a shot from the Brigadier, and later blown up along with the base by UNIT. (DW: Doctor Who and the Silurians)

Mortimus used the enslaved Chronovore Artemis to create an alternate timeline in which Morka killed the Doctor. (NA: No Future)

Behind the scenes
Morka was not named on-screen, only in the novelisation and in MA: The Scales of Injustice. He was listed as Young Silurian in the credits.

It is unknown if the alternative counterpart to Morka in Blood Heat was the same one who killed his alternative dimension of the third doctor.