Sontaran

The Sontarans (pronounced "Sohn-TAHR-ans") are a belligerent and militaristic clone race. The Doctor has encountered them at least four times during his travels.

Physical characteristics
A clone race, the Sontarans are humanoids with large, bulbous heads and stocky bodies. They have grey-brown skin and deep set features. They have three digits on each hand (two fingers and a thumb). There are apparently no female Sontarans. They are enormously strong and very tough, due to the high gravity on their home planet. One of the few ways to hurt or kill a Sontaran is via a small access port at the back of the neck. The port is normally used by the Sontarans as a feeding tube during space or time-flight.

They are typically seen wearing their distinctive battle armor, which resembles a thick grey space suit. Their helmets are round and almost featureless except for two eye holes.

Technology
The Sontarans are reasonably advanced, though all their technology was designed for use in the war with the Rutan Host. They use odd, spherical spaceships and can make advanced robots for various purposes. They can use and make a wide variety of hand-held weapons, though they usually use a thin, rod-like energy weapon. They can create around a million clones every four minutes. The Sontarans have achieved crude time-travel technology which is effective, though not on par with the Time Lords. They have been seen trying to get the Time Lords more effective time-travel technology.

History
The Sontarans are engaged in a destructive war with the Rutan Host and have been for thousands of years. It's unknown what started this conflict, but this war has driven both cultures. This has included kidnapping humans for experiments, developing their own TARDIS and invading Gallifrey, but all attempts were stopped by the Doctor.

Major appearances
Television episodes
 * The Time Warrior
 * The Sontaran Experiment
 * The Invasion of Time
 * The Two Doctors
 * Referenced in Horror of Fang Rock

Original novels
 * Shakedown