There are 2 supposed origins of the Daleks. In the first Daleks are the mutated remains of the Kaled people of the planet Skaro, who travel around in tank-like mechanical casings and are bent on universal conquest and destruction. Skaro was once home to two humanoid races: the peaceful and scientifically-advanced Kaleds/Dals (who were described as philosophers and teachers) and the warlike Thals. Following a short but terrible nuclear war between the races the Dals were mutated and became the aggressive and xenophobic Daleks.

In the second origin the Kaleds are a race of humanoid extraterrestrials  who waged war on the Thals. The Daleks originated during the Kaled-Thal War which was portrayed as a thousand-year-long war of attrition fought with nuclear, biological and chemical weapons with weapons becoming progressively less sophisticated as resources became scarcer not the short nuclear exchange previously described. It is not clear if this was the nuclear exchange between Daleks and Thals referred to in The Daleks or an even earlier conflict. The crippled Kaled chief scientist and evil genius Davros deemed the mutations from the fallout irreversible and then experimented on living cells, treating them with chemicals and accelerating the mutations to discover the eventual mutated Kaled form and ensure its survival. The mutations among the general Kaled populace were not as advanced as implied by the earlier account, and that the development of the mutated creatures that became the Daleks was engineered by Davros for his own purposes. Ultimately he used his creations to prematurely replace the non-mutated members of his race with the Daleks. These genetically conditioned forms were placed in Mark III travel machines whose design was based on his own life-support chair. The tank-like travel machines coupled with the mutants became the first Daleks.

Daleks are organisms integrated within a tank-like or robot-like mechanical casing. The resulting creatures are a powerful race bent on universal conquest and domination, utterly without pity, compassion or remorse. They have had every emotion removed except hate, leaving them with a desire to purge the Universe of all non-Dalek life. Occasionally they are shown as experiencing fear.
 
Species Name: Kaled, Dalek

Type: Mutated Amoeboid

Physical Traits: The creature has an amorphous body, slightly smaller than the man's head, and several tentacles. See the technology section for a description of the armour.

Height: Mutant 1 ft, in armour 6ft

Weight: Mutant 20 lbs, in armour 200 lbs

Mobility: The mutant can only slide and relies on its armour for true mobility

Sensory Organs: Visual

Communication: Vocal

Reproduction: Osmosis

Mutant:
INT: 3D6, WIS: 3D6, STR: 1, DEX: 1, CON: D6, CHA: 1, MR: 1, HPs: CON +D4.

Armour:
INT: 0, WIS: 0, STR: 30, DEX: 3D6, CON: 0, CHA: 0, MR: 20, HPs: 200.

Orbit/Climate: 1 AU. Very erratic, very elliptical orbit, very hot and cold extremes, frequent storms, very harsh conditions.

Atmosphere: Thin and volatile Nitrogen/Carbon dioxide with combustible volatiles.

Oceans: 5%

Gravity: 100%

Feeding Habits: Chemicals

Lifespan: Unmeasured

Technology: 10. Dalek society is one of extreme scientific and technological advancement. However, their reliance on logic and machinery is also a strategic weakness which they recognise, and thus use more emotion-driven species as agents to compensate for these shortcomings. Externally Dalek armour resemble human-sized salt and pepper shakers with a single mechanical eyestalk mounted on a rotating dome, an exterminator arm containing an energy weapon and a telescopic manipulator arm which is usually tipped by an appendage resembling a sink plunger. Daleks have been seen to be able to use their plungers to interface with technology, crush a man's skull by suction, measure the intelligence of a subject, and extract information from a man's mind. Dalek casings are made of a bonded polycarbide material dubbed "dalekanium". The lower half of a Dalek's shell is covered with hemispherical protrusions, or Dalek bumps which are part of a sensory array. The armour has a forcefield that evaporates most bullets and resists most types of energy weapon; this seems to be concentrated around the Dalek's midsection (where the mutant is located), as normally ineffective firepower can be concentrated on the eyestalk to blind a Dalek.

Dalek's own energy weapons have also been shown to be capable of destroying them. Their weapons fire a beam that has electrical tendencies is capable of propagating through water and may be a form of plasma. The eyepiece is a Dalek's most vulnerable spot and impairing its vision often leads to a blind, panicked firing of its weapon. The voice of a Dalek is electronic; the Dalek creature is apparently unable to make much more than squeaking sounds when out of its casing. Once the mutant is removed, the casing itself can be entered and operated by humanoids. For many years it was assumed that due to their design and gliding motion Daleks were unable to climb stairs and that this was a simple way of escaping them. Dalek mobility has improved over time making them to fully capable of flight, even spaceflight.

Culture: The Daleks are a malevolent, truly malicious race with no redeeming qualities at all. In terms of their behaviour Daleks are extremely aggressive, and seem driven by an instinct to attack. This instinct is so strong that Daleks have been depicted fighting the urge to kill or even attacking when unarmed. The fundamental feature of Dalek culture and psychology is an unquestioned belief in the superiority of the Dalek race, and their default directive is to destroy all non-Dalek life-forms. Other species are either to be exterminated immediately, or enslaved and then exterminated later once they are no longer useful. The Dalek obsession with their own superiority is illustrated by the schism between the Renegade and Imperial Daleks: the two factions consider the other to be a perversion despite the relatively minor differences between them. This superiority complex is the basis of the Daleks' ruthlessness and lack of compassion. It is nearly impossible to negotiate or reason with a Dalek, a single-mindedness that makes them dangerous and not to be underestimated. There is mention of a Dalek opera which was lost to posterity when the entire cast was exterminated on the opening night.

Government: A single supreme Dalek which has alternated between Davros and an Emperor Dalek.

Population: Has varied from billions to just one, and then millions again.

Home System:

Number of Stars: 1, location unknown

Star Type: B

Planetoid Belts: 0

Inner Planets: 0

Middle Planets: 1