Dalek variant

While the basic appearance of Daleks remained the same throughout their history, there were several changes and alterations to Davros' original design of the Mark Three travel machine. Variants of the "basic" Dalek design were produced both by Davros and the Dalek Emperor/Dalek Supreme (these last two representing the major power holders in the Dalek hierarchy). Both factions of Dalek used a Dalek drone for basic combat.

The Time Lords studied and recorded the variants of the Daleks in their Dalek Combat Training Manual, published during the Last Great Time War. (PROSE: Dalek Combat Training Manual)

Davros' variants
Early in his design work Davros created Spider Daleks, which walked on a set of spider-like legs, rather than gliding across the ground. These were succeeded by Daleks known as "Strider Daleks". (PROSE: War of the Daleks)

Following his awakening from cryogenics and an encounter with the Dalek Supreme, Davros set up a base of operations on Necros and began creating Daleks of human origin. As the name suggested, these Dalek variants were created using humans, rather than Kaled mutants. This process also employed a Glass Dalek. The casings of these Necros Daleks were distinguished from the opposing grey Daleks by their white-and-gold livery, (TV: Revelation of the Daleks) designated as "Type VI Dalek" by the Time Lords. (PROSE: Dalek Combat Training Manual)

Davros later refined his Daleks into the Imperial Daleks, (TV: Remembrance of the Daleks) designated as the "Type VII Dalek". (PROSE: Dalek Combat Training Manual) Naming himself Emperor, Davros operated a unique casing. (TV: Remembrance of the Daleks)

Dalek Emperor / Dalek Supreme variants
The Dalek Emperor and Dalek Supremes were marked by having several designs that differed significantly from other Daleks. They also created altered designs under their own command.

Dalek Puppet Emperors also existed. (PROSE: Meet the Doctor)

During the early Empire led by the Golden Emperors, Dalek variants included the War Leader Dalek, the red Storm-Blast Dalek, (COMIC: City of the Daleks) the Astrodalek, (COMIC: The Rogue Planet) Dalek transport officials, Dalek miners and Dalek metalworkers. (PROSE: Hostage!)

Identified by the Thirteenth Doctor, reconnaissance scouts were the first Daleks out of Skaro. One Reconnaissance Dalek landed on Earth where, after it was first defeated, reconstructed a unique bronze casing. (TV: Resolution)

In the Mechonoid Incident, silver Daleks designated as Pursuer-Daleks were tasked with pursuing the First Doctor through time. They were supported by a variant of the earlier War Machine model distinguished by their dark domes. (TV: The Chase, AUDIO: The Daleks)

A subordinate Dalek distinguished by its red dome supported "a red Dalek leader" during the conflict against the Space Security Service. (PROSE: Dalek Combat Training Manual)

As observed by Landinalakallinian, Dalek Captains commanded Dalek battalions, each battalion being comprised of two equal-sized companies commanded by a Dalek Lieutenant. Dalek Captains and Lieutenants did not seem to be distinguishable from exterior appearance, with the Gallifreyan professor suggesting that they relied on forms of radio identification signals to identify each other instead of more obvious rank markings. (PROSE: The Dalek Problem)

During the Second Dalek War against humanity, the Supreme Dalek was supported by a Dalek Inquisitor General, designated by the humans as Dalek X. (PROSE: Prisoner of the Daleks) Bombardier Daleks served in the war. (PROSE: Lucifer Rising)

In the aftermath of the Dalek-Movellan War, the Supreme Dalek was assisted by subordinate ranks including an Alpha Dalek, Beta Dalek, Gamma Dalek, Delta Dalek and Epsilon Dalek. (PROSE: Resurrection of the Daleks, Revelation of the Daleks)

In the conflict against Davros, Psyche Daleks served the Supreme Dalek. (COMIC: Emperor of the Daleks!)

The Dalek Time Controller was a time travelling Dalek which also operated under the title Dalek Litigator. (PROSE: The Dalek Generation, AUDIO: Patient Zero) Following its loss, it was replaced by the Dalek Time Strategist. (PROSE: Dalek Combat Training Manual)

At the command of the Dalek Emperor, the Cult of Skaro were created. (TV: Doomsday)

Shared design variants
Both Davros and the Dalek Emperor were known to use Special Weapons Dalek variants in combat situations: Davros used one during the Shoreditch Incident, whilst the Dalek Emperor utilised several in various campaigns. (TV: Remembrance of the Daleks, COMIC: Fire and Brimstone, PROSE: War of the Daleks, AUDIO: The Genocide Machine)

2254 invasion
In what may have just been a simulation created by the energies of the Land of Fiction, (PROSE: Head Games) Davros led the Daleks in an invasion of Earth in the year 2254, allied with a mobile and armed bronze Dalek Emperor. They were supported by the Battle Commander Daleks, a group of twelve Daleks who directed the Dalek war efforts. Dalek variants which participated in the invasion included Super Daleks, Elite Battle Daleks, red Daleks in hoverbouts which were designated as Flying Daleks. In addition, distinct Super Guardian Daleks served to secure the foothold in major cities including London, Paris, New York and Tokyo. Back on Skaro, Redesigned Daleks were present among the ranks. (GAME: Dalek Attack)

Restoration Empire
Following an Imperial Dalek victory in the Imperial-Renegade Dalek Civil War was the Restoration Empire, which may have only came into existence due to divergences in time. With refined "Type VIII"-shaped casings, this Empire was led by a new golden Emperor who established a Dalek Time Squad made up of Time-Sensitive Daleks. Supported by Dalek drones who were coloured like the earlier silver Daleks, (PROSE: The Restoration Empire) subordinate to a grey Dalek. (COMIC: Defender of the Daleks) The Dalek Prime Strategist was an old Dalek who was distinguished by his aged Dalek War Machine casing. The Dalek Time Commander was a silver Dalek distinguished by its silver sense globes. The Scientist Dalek's silver casing was distinguished by a red dome and livery. Dalek Executioners were repurposed Special Weapons Daleks that now operated conventional casings distinguished by a black dome and livery with a red eye lens and claw manipulator. (PROSE: The Restoration Empire)

Last Great Time War
The Dalek Emperor in the Last Great Time War was housed in an immense bronze casing (TV: The Parting of the Ways) and was designated by the Time Lords as "The Emperor Type II". (PROSE: Dalek Combat Training Manual)

Prime Dalek was a rank in the Dalek hierarchy which the War Doctor was unfamiliar with when he first heard it during the Last Great Time War. (AUDIO: The Thousand Worlds)

Whilst in the Neverwhen, the Daleks evolved through several variants including Special Weapons, spider degradations, and Diamond Daleks. (AUDIO: The Neverwhen)

The Eternity Circle were a council of five Daleks distinguished by their blue casings with silver domes and globes. They created the Predator Dalek, intended for the War Doctor to become its Dalek Mutant. (PROSE: Engines of War)

A unique unit during the conflict was the Dalek Time Strategist, the successor to the Dalek Time Controller, its casing a purple coloured variation of the red Dalek Supreme model that first appeared in the Second Dalek War. (AUDIO: The Shadow Vortex)

Distinguished by its black casing with a red eye lens and multiple appendages from its weapons platform, the Overseer was a unique Dalek designed as an expert in genetic manipulation, the mutant itself being a mixture of other species. It was exterminated by its subordinates after failing in its mission. (AUDIO: Planet of the Ogrons)

Post-Last Great Time War
Following the Last Great Time War several new Dalek variants were created, both embryos, not technically a variant, but rather an attempt to recreate the original Dalek mutation. (TV: Daleks in Manhattan)

Following Dalek Caan's intervention, a new Supreme Dalek was created, along with Vault Dalek to guard and maintain the vault of the Crucible. (TV: The Stolen Earth)

After the fall of the New Dalek Empire, a trio of bronze Dalek drones, (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) found themselves stranded in 1941. They concocted a plan to have the Eleventh Doctor identify them as Daleks to the Progenitor, an ancient Dalek instrument containing "pure Dalek DNA". This involved two of the Daleks being disguised as green Ironsides, ostensibly robots created for the British war effort in World War II. Once this plan succeeded, the Progenitor created five new specimens, with five larger and colour-coded cases: a white Supreme, orange Scientist, blue Strategist and red Drone Dalek along with the unique yellow Eternal Dalek. Naming themselves the New Dalek Paradigm, these five proceeded to destroy their "inferior" forebears, and fled to their "own time" through a time corridor to start anew a restored Dalek legacy. (TV: Victory of the Daleks) In one instance, a Chief Strategist oversaw subordinate Strategist Daleks, to whom it appeared identical. (COMIC: The Only Good Dalek)

In a alternate timeline which was negated by the Doctor, the New Paradigm was led by a blue Emperor Dalek. (GAME: City of the Daleks) Later, whilst collecting the Eternity Clock, the Doctor fought a purple Dalek Emperor. (GAME: The Eternity Clock)

In the Total Collapse Event Incident, the Daleks, having been all but erased from history, were reduced to afterimages, the Stone Daleks, before the Eleventh Doctor rebooted the universe in Big Bang Two. (TV: The Big Bang)

While the New Paradigm initially mass-produced its new design of casing, (GAME: City of the Daleks, COMIC: The Only Good Dalek) the many defeats that the Eleventh Doctor would go on to inflict upon this design caused other species to lose their fear of the Daleks. Reorganising their command structure, the Paradigm reestablished the Parliament of the Daleks under the leadership of the Prime Minister of the Daleks who promoted the Paradigm's first style of casing to a seldom seen "officer-class" and returned the active infantry to the designs used in the Last Great Time War. The five founders, retaining their original casing design, were reduced to a token presence in the Parliament with several Red Drones overseeing their bronze subordinates. (TV: Asylum of the Daleks, PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) The thousand of bronze Daleks in the Parliament were designated Dalek governors. (PROSE: Dalek Combat Training Manual)

As part of the Dalek Project, the Daleks saw that Proto-Daleks were constructed by the British and the Germans during the First World War, resulting in distinct British Proto-Daleks and German Proto-Daleks. The Daleks themselves fielded Aqua-Dalek units underwater. In 2017, human archeologists assembled a Dalek casing which the Eleventh Doctor named a Quasimodo Dalek. (COMIC: The Dalek Project)

In time, the Paradigm casings seemed to vanish from the post-War empire. Instead, bronze casings remained the standard design of drones, while Black Dalek and the red Supreme casings re-emerged as officer classes. Older casings designs like the Dalek War Machine and Imperial Special Weapons Dalek also returned. (TV: The Magician's Apprentice, The Witch's Familiar)

Bronze Dalek drones designated as boarding Daleks were used in the conflict with the Combined Galactic Resistance. (TV: Into the Dalek) Death Squad Daleks and Dalek Executioners used bronze casings. (TV: Revolution of the Daleks, Eve of the Daleks)

Splinter groups
The first generation of humanised Daleks appeared as basic silver Daleks who rebelled against their counterparts as well as the black-domed Emperor's Personal Guard. (TV: The Evil of the Daleks) The casings of the humanised Daleks that lived on Kyrol came in a diverse range of colours. Alpha, of the original generation, changed his casing to serve as Red Dalek leader. His second was a Black Dalek, named Makkith. Below them were the Blue Daleks, the only other humanised Daleks to be armed with gunsticks. The majority of the humanised Daleks, however, were distinct from the Skarosian Daleks in that their weapons platforms sported only a manipulator arm, with a vacant space where the gunstick would be; these disarmed Daleks were, however, able to use their psychokinetic energy to defend themselves. Green Daleks such as Adellus functioned as scientists, while other Daleks were coloured Yellow, Orange and Purple. (COMIC: Children of the Revolution)

The Orcini New Daleks were intended by their pacifist creator, Gonzo Orcini, to be a refined version of the "Old Daleks" created by Davros. Their hierarchy included Third Class Dalek Leader and First Class Dalek Leader. (PROSE: War and Peace)

Mutant Daleks were created on Red Rocket Rising by the human Professor Martez. They were exterminated by the original Daleks. (AUDIO: Blood of the Daleks)

Having been resurrected with traces of human DNA, the Reconnaissance Dalek used Leo Rugazzi to create a New Dalek Army, which were ostensibly "Defence Drones" to protect the United Kingdom. They attempted to conquer Earth only to be exterminated by the Death Squad Daleks. (TV: Revolution of the Daleks)

Other variants
On Skaro in the far future, the First Doctor saw Daleks patrolling Zone X. (COMIC: The Test of Time)

Parallel universes
In a parallel universe, the Thaleks were a species that conquered half of Mutter's Spiral. Their war cry was "Annihilate!". (AUDIO: Auld Mortality)

The Alliance Daleks, so-named by the Earth Alliance to distinguish them from the Enemy Daleks during the Enemy-Alliance Dalek War, were Daleks from a parallel universe, who were created by the Mentor. They crossed over to N-Space at the end of the Second Great Dalek Occupation. (AUDIO: Project Infinity)

In one of the infinite parallel universes of "possible space", the Daleks were half-insectoid, half-humanoid mutants in casings that had a spider-like appearance, able to fold and unfold. (COMIC: Fire and Brimstone) These Daleks were also carnivorous, able to devour those they killed. (PROSE: The Chronicles of Doctor Who?)

Behind the scenes

 * In the film Dr. Who and the Daleks, a Black Dalek, supported by a Red Dalek, led blue Dalek drones. In Daleks' Invasion Earth 2150 A.D., a Gold Dalek, supported by a Black Dalek and a Red Dalek, led silver Dalek drones.
 * Upon completing the game The Last Dalek, the player achieves a rank depending on their progress. From lowest to highest; Standard Dalek, Imperial Dalek, Supreme Dalek, Dalek Prime, Dalek Ultima, Dalek Emperor. Distinctly, the rank of "Dalek Ultima" is not derived from any story.
 * The online game Dalek Hack features a bronze-type casing divided into three sections, the top dome and grating section, the middle weapons platform and the bottom base unit. For customisation, a choice of six colours can be applied to each of the sections: a Black Dalek with gold livery matching that of the Dalek Inquisitor General with the colours of the following Daleks reflecting the five archetypes of the New Dalek Paradigm, being Red, Blue, Yellow, Orange and White.
 * The cover of Gallifrey: War Room 1: Allegiance featured new Time War-era Dalek models rendered by James Johnson, the Dalek Commander and the Reconnaissance Dalek. Ahead of release, Johnson released a closer look at his designs. He clarified that the accompanying text wasn't in any way official, and that he added it "just for fun".