Skaldak

Grand Marshall Skaldak was an Ice Warrior who the Eleventh Doctor referred to as "sovereign of the Tharseesian Caste" and "vanquisher of the Phobos Heresy." The Doctor also claimed that his foes honoured him so much they carved his name into their flesh just before they died.

He commanded a fleet called the Nix-Thassis, with his daughter beside him.

Eventually, he wound up frozen in the ice at the Earth's North Pole around 3000 BC. 5,000 years later, in 1983, Soviet scientist, Professor Grisenko, found him.

Impatient enough to not wait until returning to Moscow, a crew member of the submarine aboard which Grisenko was serving thawed Skaldak with a blowtorch. Disoriented from the sudden awakening, Skaldak went on a brief rampage that sent the submarine to the bottom of the ocean. After an encounter with the Doctor and the submarine's crew during which he was knocked out and captured, he learned how long he been in the ice, sending him into a state of grief. This was exacerbated when he attempted to contact his fellow Ice Warriors, but they didn't respond.

Feeling he had nothing left to lose, he left his armour to learn more about the submarine and the humans. As soon as he learned about the nuclear missiles on board, he decided to fire them and wipe out humanity as payback for attacking him.

However, just as he was about to fire them, another encounter with the Doctor made him hesitate, and the Doctor's companion Clara Oswald appealed to the memory of Skaldak's daughter to make him stop.

Shortly, fellow Ice Warriors arrived to rescue him, and he left on their spaceship, and deactivated the warheads as a final show of mercy before he left Earth. (TV: Cold War)

Personality
Like most Ice Warriors, Skaldak was honorable but when he was desperate he threw away his honor and started crawling around the submarine out of his armour, something that was considered highly dishonourable among the Ice Warriors. Believing that he was the last of his kind, Skaldak decided that honour didn't matter anymore and devoted himself to getting revenge instead. He was ferocious in battle, and his reputation was legendary; it was said that his victims carved his name into their skin before they died. He tore most of his victims to peices in the submarine, showing that he was very bloodthirsty and possibly a bit sadistic.

However Skaldak did have a sensitive and sentimental side, and was upset by the death of his daughter and in honour of her memory, he stopped his murderous rampage after Clara reminded him that he would cause other people to go through the same pain he'd gone through when he lost his family if he went through with his plan. Skaldak showed his honor and mercy by deactivating the warheads before he left Earth, having originally intended to use them to start another World War. He also showed respect to fellow warriors, even if they were his enemies, and complimented the Captain on his strategy of negotiating "from a position of strength".

Behind the scenes

 * Skaldak is the first and, to date only, Ice Warrior to be seen on-screen outside of his armour.
 * Although we never see anything other than his hands, arms and face clearly, the rest is either blurred or out of shot.