The Sontarans were humanoids with large, bulbous heads and short stocky bodies. They had grey-brown skin and deep set features. Sontarans generally had three digits on each hand (two fingers and a thumb). Some Sontarans also had vestigial hair, generally in the form of beards, which grew white with age. Sontaran blood was green.
The Sontarans reproduced by cloning, meaning each Sontaran was nearly identical to each other. There were some instances in variation, such as the number of fingers or skin colour. The mass cloning techniques they possessed allowed their hatcheries to produce up to 1,000,000 Sontarans in 4 minutes. All appeared roughly the same age, with the exception of General Sontar, who appeared older. The rare Pureblood Sontaran had increased status and were higher in the hierarchy. Occasionally, genetic defects would crop up and the afflicted Sontarans would be sent to work in menial labour.
Due to Sontar's high level of gravity, the Sontarans had great strength and resilience in lower gravity environments like Earth or Gallifrey. Despite this strength, Sontaran muscles were designed for load bearing rather than leverage. They were also vulnerable to Coronic acid, which burnt, or in some cases even disintegrated them. If severely wounded, a Sontaran would enter an anabolic coma. In most cases, they would then die, but sometimes they would later wake up. They absorbed energy via the Probic Vent on the back of their necks. This vent was also their crucial weakness, as any sudden contact to the vent would stun them. The penetration of a sharp object into the vent would kill them.
The Sontarans were a martial species, obsessed with war. The highest honour for a Sontaran was to serve in the Imperial Fleet and to be disallowed soldiering was the most dishonourable fate for a Sontaran. Fighting for other species was an equally dishonourable fate. Sontarans did not fear death, and they would rather be court-martialled than show pain to others. They considered it honourable to face battle open skinned, without a helmet on. Though they would make alliances with other species, they felt no need to keep them. Their idea of a dishonourable and shameful death was to die peacefully, and the family of a Sontaran that died in his sleep would often make up a story to show them dying on the battlefield. An old and sick Sontaran would often sign up for the military so that he could die whilst fighting.
Among those Sontarans that possessed five digits on their hands, it was generally considered for such individuals to be placed as intelligence operatives who had enhanced skills as well as instincts. However, it was often noted that these agents had a tendency to be paranoid.
Despite being a clone race, the Sontarans still retained the concept of betrothal, which was roughly analogous to ending hostilities by killing your enemy. Within their society, there was also a rigid clan structure all of which had different genetic markers. As well, clans still had great influence despite being a clone species, such as the Gunnar Clan. Sontarans were known for Quicksand Wrestling. Sontarans used a Base-6 counting system.
The Sontarans were reasonably advanced, though all their technology was designed for use in the war with the Rutan Host. They often used spherical spaceships and could make advanced robots for various purposes.
The Sontarans could use and make a wide variety of hand-held weapons, though they usually used the Rheon Carbine, a thin, metallic weapon, which was designed to optimally fit the Sontaran hand. The weapons were used for energy projection and hypnotism. The Sontarans also utilized rifle laser weapons during the assault of 2009, which fired bright beams of red light that could kill a Human without any exterior damage.
The Sontarans also made use of fragmentation grenades, which could destroy everything in a certain area.
The Sontarans used spherical vessels, which were covered in square plates. They were generally only large enough for one Sontaran. Some had cloaking capabilities.
The Sontaran motherships were similar in shape to the scoutship, but had 4 claw like appendages coming out of the top and bottom. The scout ships were attached to the mothership and could be released when needed.
Sontaran War-Wheels were combat vessels shaped roughly like a bow tie, with two rotating 'wheels' either side of a central spherical core. They were capable of planetary landings.
When on a planet, the Sontarans would travel by the means of aircraft. These aircraft looked like the bottom half of a Sontaran ship, with seats and controls on the top half.
By the 12th century, Sontarans already used crude time-travel technology, utilising osmic projection, though nothing comparable to Time Lords. In the 20th century, they made other attempts to obtain more effective time-travel technology, specifically those of the Time Lords.
Sontarans adapted teleportation technology using generators situated at the area of materialisation.
Sontarans wore distinctive battle armour, which resembled a thick and bulky grey space suit. Their helmets were dome-shaped and almost featureless except for two eye holes and a small, flat crest running from the forehead to the back of the neck. They generally carried around their rod-like weapon and a translating device. During a period in the early 21st century Sontarans had blue, less flexible, armour in a similar design.
Sontarans used two methods of controlling other individuals. They could take over their mind with hypnosis, or control them with devices attached to the neck.
The Sontarans were capable of creating around a million clones every four minutes, which allowed them to sustain massive casualties. These clones were fed using the probic vent, which was the Sontaran's only weak spot. These clones were grown in vats and were nourished by sezerfine gas.
The Sontarans could heal their wounds with a device called a tissue rectifier, which was a stubby, tubular device.
Styre used a miniature camera and a force field while studying Humans.
During the mission to make Earth a clone planet, the Sontarans made a Cordolaine field around themselves that causes metallic copper to expand; when the copper is in the jacket of a bullet, it becomes jammed in the gun's barrel, rendering it useless.
In their early history, the Sontarans were split into clans, which would fight amongst themselves. The original Sontarans appeared ganglier and more like Humans. The survivors of these civil wars joined forces and set their aggression on aliens instead.
The Sontarans eventually discovered cloning and adapted it to their own use, abandoning normal reproduction. Prior to the war with the Rutans, the clones forced the purebloods off-world.
The cloned Sontarans were engaged in a war with the Rutan Host. During the Millennium War, though, Sontarans and Rutans briefly joined forces.
In the 13th century, Linx, a scout, landed in England and claimed it for the Sontaran Empire. He proceeded to make an alliance with Irongron, a local warlord, and to transport scientists from the late 20th century into the past using his osmic projection. He would then hypnotise them in order to make them work on his ship.Later, in the year 1522 AD, a Sontaran scoutship crash landed on Earth in China. As a result of the incident, their hyperspace transmitter was damaged and they required a replacement crystal in order to summon reinforcements as well as take over the planet. There, they formed a partnership with the Abbot Hsiang and Yueh who knew them as the "bronze men" where they used their hypnotic technology to test enhance his fighting abilities. The Emperor of China learnt of the enhanced fighting skills of the monks and came for a demonstration. This was all part of a plan by the Sontarans to kill the Chinese Emperor as he possessed a quartz crystal sufficient to power the hyperspace transmitter and thus placed a hypnotic suggestion designed to turn the monks against the Emperor in order to kill him. However, the Doctor intervened and had K-9 recorded the trigger words and broke the spell but not before Chang went into a berserker attack that killed the Sontarans as a result of him hearing the command phrase once.
In 1609, along with the Rutans, the Sontarans participated in the summit of military powers throughout Mutter's Spiral in the Armageddon Convention, which convened in Laputa, a floating island in the sky near Venice.
At some point during the 20th century, Edgar Nelson-Stanley met with the Sontarans. He believed they were "the silliest race in the galaxy".
In the 1980s, the Sontaran Warburg investigated the possibility of using time ships in order to win the war. At the same point in time they were involved in a battle with the Rutans in the Madillon Cluster. Neither attempt was successful.
In 2009, the Sontarans were losing the war against the Rutans. To counter this, the Tenth Sontaran Battle Fleet (led by General Staal) made plans to convert Earth into a cloning world, and carried them out with the help of Luke Rattigan. The Sontarans used a form of hypnosis on the workers of the ATMOS factory, forcing them to start shipping out devices that contained gases poisonous to humans, contained inside plates attached to the Sat-navs they sold. When the Doctor attempted to meddle, the Sontarans activated all the devices already deployed in cars, releasing the poison gas and choking people nearby. The fleet was eventually destroyed by Rattigan.
Following this attempt, Commander Kaagh was left as the last survivor of the Tenth Sontaran Battle Fleet after he crashed to Earth. He used Professor Nicholas Skinner to bring satellites crashing into Earth's nuclear power plants. He wanted to take Sarah Jane Smith to Sontar for the Doctor's crime and for her knowledge of the Sontarans. The plan was stopped when Chrissie Jackson disabled Kaagh with her high heeled shoe, but he came round and was forced back to Sontar in his pod.
Following this failure, Kaagh became a mercenary for the Bane. He met Mrs Wormwood while looking for the remains of Horath and they agreed to work together. After finding the mind of Horath, he followed Wormwood to Earth, where they took the Tunguska Scroll from Sarah Jane and kidnapped Luke Smith. The alliance started to break down when Mrs Wormwood sided with Luke over Kaagh, ending when she betrayed and disabled him. Seeing that he had lost, he dragged Wormwood into the wormhole containing Horath.
In January 2010, one Sontaran named Jask was on Earth and was chased by Martha Jones and Mickey Smith. He managed to get away and tried to kill them with a sniper rifle but was knocked out by the Doctor.
At some point during the 26th century, the Sontarans sent in Commander Steg to conquer Jekkar in order to create a buffer around Sontar. Though he had no difficulty with the Humans, the Jekkari, led by the Doctor, were able to fight back effectively. The surviving Sontarans destroyed their bases and abandoned the planet.
Some time later, an expedition was made to go to Sentarion and take advantage of the wormhole connecting it and Ruta III to kill the Rutan Queen. Though the Sontarans tried to keep this information classified, a Rutan spy known as Karne was able to learn that the information had leaked out and tried to return to the Rutans. Commander Steg was sent in to redeem himself and kill Karne. He was able to track it to the space yacht Tiger Moth, where it had hidden in the ship. During the course of his investigations, his soldiers were whittled down by Karne and the Human crew. Eventually, Karne was killed and all the Sontarans were believed to be killed. In reality, Karne was able to clone himself before his death and Steg was able to pull through.
The second Karne was to able escape to Sentarion, followed by the Doctor, his companions and the survivors from the Tiger Moth. Commander Steg was able to follow them with a War-Wheel and forced the Doctor to open to wormhole to Ruta III. The War-Wheel was sent through, but the Doctor was able to reverse the polarity of the wormhole, meaning the War-Wheel would never get to Ruta III. When Steg tried to kill the Doctor in revenge, a fight began, leading to the death of Karne and the the Sontaran forces.
During either the 25th or 26th century, the Rutans destroyed the Sontaran homeworld, Sontar, with photonic bombs, though some escaped with the Sontaran racepool. At the same time, the Sontarans encountered the Pureblood Sontarans. Due to the intervention of the Doctor, the cloned and pureblood Sontarans decided to pool their resources and Marshal Stave promised to remove the Sontarans' memory of Humans from the racepool.
Many thousands of years later, at a time when the Earth had been abandoned for 10,000 years, the Sontarans were separated from the many human worlds like GalSec throughout Mutter's Spiral by a buffer zone. The Grand Strategic Council planned to invade the galaxy, but they had to abandon that plan when a scout, Field Major Styre, was killed while trying to assess the strengths and weaknesses of the humans. After this, the Doctor bluffed, telling the Sontarans that their battle plans had been captured, so they would have to call off their invasion.
The Sontaran mining ship Betrothal of Sontar was sent to Serac as a form of demotion. Colonel Snathe, a pureblood Sontaran, believed that the Thanatos was located on Serac, but his attempts to find it were unsuccessful and crew became restless and insubordinate. When the Tenth Doctor arrived, Snathe forced him to find the Thanatos - but when Snathe tried to control it, the Thanatos decided that the Sontarans were stagnant and Sontar needed to be destroyed. Though Lerox showed that there was still hope for the Sontarans, Snathe was killed when the Inuk shoved him outside during a Silverfire.
The Carpalian Witch's favourite hunt was when she hunted a Sontaran. Since her pheromonal lure was ineffective, she waited in his ship for 6 weeks until she stabbed him in the probic vent when he was about recharge.
Though the Sontaran Linx, in the 12th century, merely considered the invasion of Gallifrey as a speculative possibility, the Sontarans, in concert with the Vardans did invade, until beaten back by then-Lord President the Doctor.
During another period of Time Lord history, the Warburg, led by General Sontar himself, the Warburg's supreme commander, and the Rutan Host convened on Gallifrey to meet face to face without violence.
The Sontarans were also not 'allowed' to fight in the Last Great Time War, which according to General Staal was the greatest war of all time.