General Staal

General Staal, also known as Staal the Undefeated, is a Sontaran general. His main weapon is a Sontaran baton, a device which fires energy beams that can injure, stun or kill a target, as well as repair minor damage to Sontaran technology.

Personality
Staal has a great love of warfare and is unafraid of Death. He is also manipulative and treacherous. He claims that the Sontarans "say the same of humans" when he's asked by Claire how they tell each other apart, showing that he has no respect for humanity.

Role
Staal is first seen in the Seventh episode of Season 1, where he's the waiter of a fast food restaurant called KFS (Kentucky Fried Sontaran), owned by Davros. He plans to make more Sontarans from the medieval inhabitants through the use of a special sauce that slowly turns anyone who consumes it into a Sontaran. Lots of villagers consume this sauce, including Merlin and Tyrant. However, the Eleventh Doctor and Claire foil his plan and create an antidote from what's left of the sauce.

In Season 2, Staal informs the Doctors that there's a small group of people that will be converted into Cybermen if they lose a race against an Elite Cyberman. He is incredulous when he sees that the Doctors manage to defeat the Cyberman.

In Season 3, he is seen when Rassilon plans to capture Moomin and turn him into a Sycorax. He is then seen running out when the Eleventh and Fourth Doctors return Moomin to normal. He appears again in the Season 3 finale when he rides the Cyberking.

In Season 4, he forms an alliance with the Ninth Doctor and assists him in resurrecting an evil Time Lord named Morbius. Unfortunately, he dies during a "Survivor" style tournament when Morbius decides to kill him so that he gets voted off due to being dead.