Dalek drone

The Dalek drone was the most common variant of Dalek. (GAME: City of the Daleks) They were used as the main "foot soldier", which led to them very occasionally being called warrior Daleks. (PROSE: War of the Daleks)

Pre-Time War
The original Daleks were created by Davros, who originally described them as his Mark III Travel Machine. These early Daleks had armour cast in gunmetal grey and black. (TV: Genesis of the Daleks)

By the time the First Doctor first encountered the Daleks, the Dalek drones lacked slats on their midsection and instead depended on static electricity from the floors of the Dalek City for power. (TV: The Daleks)

The Dalek drones seen in England during the 22nd century Dalek invasion had radio dishes mounted on their backs for external power and larger bases. (TV: The Dalek Invasion of Earth)

The Daleks later once again adopted vertical slats as a more efficient means of drawing external power from their surroundings. (TV: The Chase onwards)

Later, the Daleks readopted the gunmetal grey colour scheme used by the Mark III Travel Machines, (TV: Day of the Daleks) although the Daleks that were stranded on Exxilon had a silver and black colour scheme. (TV: Death to the Daleks)

The gunmetal and black design continued to be the standard for the Dalek Empire for many years. However, during his time at Tranquil Repose Davros genetically engineered an entirely new breed of Daleks from the Resting Ones - these mutants were completely loyal to Davros, and had distinctive white casings with gold sensor globes, neck grating and limbs. Following the eruption of the war between these and the original Dalek Empire, these came to be known as the "Imperial" faction, now featuring all-gold appendages and white bases and - for the first time - the ability to hover under their own power. Meanwhile, the original Skarosian faction of Daleks came to be known as the Renegade Daleks, and phased out the traditional gunmetal casings in favour of a battleship grey and black colour scheme. (TV: Remembrance of the Daleks)

The Dalek drones were still identified by their grey casings at the beginning of the Second Dalek War of the 26th century (TV: Frontier in Space, Planet of the Daleks) but the casings were altered as the war went on. By the end of the war, Dalek soldiers had a much heavier and more solid look with a distinctive bronze finish, an expanded base, larger cylindrical indicator lights, and a blue-lit eyepiece. (PROSE: Prisoner of the Daleks) However, they reverted to the simpler grey casings once again after the war was finished. (TV: Destiny of the Daleks, Resurrection of the Daleks, Revelation of the Daleks, Remembrance of the Daleks, PROSE: War of the Daleks)

Time War and aftermath
During the Last Great Time War, the Daleks reintroduced the bronze casings from the Second Dalek War. The basics of the design became standard for all Daleks. (PROSE: Prisoner of the Daleks, I Am a Dalek, Engines of War, TV: The Last Day, The Day of the Doctor, Dalek) This design was much more advanced than any previous models, with a swiveling mid-section that allowed the Dalek a 360-degree field of fire and a force field that fully disintegrated approaching bullets. The design also added a new feature to the eyestalk: if something was obstructing its vision (such as paint), a heat discharge could melt the obstruction. It was also able to regenerate itself by absorbing electrical power and the DNA of a time traveller. The manipulator arm was also able to crush a man's skull in addition to the technology interfacing abilities shown by earlier models. (TV: Dalek, The Stolen Earth) The four unique Daleks who comprised the Cult of Skaro had the built-in "Emergency Temporal Shift" functions. (TV: Doomsday)

New Dalek Empire
The drone casings of the New Dalek Empire were identical to the bronze casings of the Time War Dalek Empire. One minor variation, the Vault Daleks (found aboard their space station the Crucible) possessed a specialised manipulator arm with eight "digits" but were otherwise identical. The mutants inside all the New Empire casings were grown from the cells of Davros' own body.(TV: The Stolen Earth) The New Dalek Empire was ultimately destroyed by the Meta-Crisis Tenth Doctor, however. (TV: Journey's End)

New Dalek Paradigm
When the Dalek race was successfully restored using the Progenitor device, the first five individuals of the New Dalek Paradigm emerged. Their casings were larger than their predecessors' and the new drone was bright red, but other than the colours was otherwise no different from its superiors such as the Strategist Dalek and the Scientist Dalek. (TV: Victory of the Daleks) While the design of the red Paradigm drone was initially mass-produced, (GAME: City of the Daleks, Return to Earth, The Eternity Clock; COMIC: The Only Good Dalek) the Daleks ultimately chose to return to using the smaller bronze Time War model as the standard drone, with the larger red version being elevated to a higher position and given a more metallic burgundy colour. (TV: Asylum of the Daleks, The Time of the Doctor, Into the Dalek,; COMIC: The Dalek Project; PROSE: The Dalek Generation)

Daleks, which were possibly of the paradigm, used casings seen throughout their history on Skaro. Dalek drones in bronze casings, sliver casings, and at least one grey casing were present at Dalek control in the rebuilt Dalek City. Davros was also present on Skaro, and was dying. He wished to see the Doctor again, and the Twelfth Doctor,, and Clara Oswald were brought to Skaro. Inside Dalek control the Daleks kept the The Doctor's TARDIS, and the Supreme Dalek revealed it would be destroyed. Missy briefly spoke to the group of Daleks and offered to give them the TARDIS so the Daleks could be more powerful then ever before, but the Supreme Dalek refused and ordered "maximum extermination." The Dalek drones, as well as other Dalek variants, fired and presumed to have exterminated Missy and then Clara,(TV: The Magician's Apprentice) but were unaware they have escaped at the last moment by teleporting away at time they were meant to be killed using their vortex manipulators.(TV: The Witch's Familiar) They then "destroyed" the TARDIS, (TV: The Magician's Apprentice) but due to the Hostile Action Displacement System it survived.(TV: The Witch's Familiar)

Afterwards the Twelfth Doctor stole Davros's chair and entered with it. The Dalek drones and other Daleks inside attempted to exterminate him, but were unable to due to the force field surrounding it. The Doctor told the Daleks he wanted Clara Oswald brought to him safe, alive, and unharmed, and this was heard by Missy and Clara, who had entered the sewers containing decaying Dalek mutants. The Doctor was stopped by Colony Sarff and brought back to Davros, who truly planned to use the Doctor's regeneration energy to prolong his life and make the Daleks on Skaro Dalek-Time Lord hybrids. Davros showed the Doctor that he was living off the Daleks, and as long as they their hearts beated his did as well. Davros revealed this was because his Daleks had a genetic flaw: respect and mercy for him. The two bonded in the infirmary, but Missy and Clara were also busy. In the sewers Missy had tricked Clara in forcing at Dalek to come. The Dalek drone arrived in the sewers, but Missy used a dwarf star alloy brooch to damage the Dalek's casing. The Dalek stated the damage was insignificant, but Missy rebutted stating that they were surrounded by old angry Daleks. The decaying Dalek mutants attacked the Dalek drone and killed it, and afterwards Missy removed the dead mutant and had Clara get inside the bronze casing, but inside others could not hear what she said, but that the casing changed it to fit more into Dalek like vocabulary. Now disguised as a Dalek, Clara escorted Missy into the Dalek city, and she claimed she was allowed to live because she was a prisoner of value, being a Time Lady. Missy and the disguised Clara entered Dalek control, and there Missy told them she had Clara Oswald, but not long after the Daleks stopped moving and regeneration energy entered them, as Davros had implemented his plan and had Colony Sarff trap the Doctor to the cables. Every Dalek on Skaro was being given Time Lord regeneration energy, and Davros believed this was in line with a Gallifreyan legend about the Hybrid. Missy understood what was happening and ran to save the Doctor, leaving Clara behind in the casing that she was unable to properly speak out of. Missy arrived to the infirmary and used a gunstick to free the Doctor, which also killed Colony Sarff. The Supreme Dalek, Dalek drones, and other Daleks reactivated, and saw that they were more powerful and the experiment was successful. The Daleks praised Davros, and he said his life was prolonged and that his "children" sung that he was he was the "creator and savior of the Daleks." The Doctor however had known what Davros was doing, and allowed Davros to do his plan as it also fed regeneration energy to the decaying Daleks in the sewers. The decaying Daleks began to rise up, and would soon destroy the city. In one of the hallways of the city the disguised Clara ran into the Doctor. The Doctor believed it to be another Dalek, however Missy claimed it was a Dalek that had killed Clara. Clara however was able to talk and have the casing say "mercy," leading to the Doctor having her think the word open to get her out of the casing. The Doctor told Missy to run, and he and Clara made it back to where the TARDIS had been "destroyed" as the city crumbed around the Daleks drones and other variants. The Dalek Supreme ordered for the two to assist or be exterminated, and the Doctor told them to "exterminate away." The attempted extermination failed however, as the TARDIS force field remained. Using the sonic sunglasses the Doctor reassembled the TARDIS, and the Doctor and Clara escaped the Dalek City as the decaying Daleks continued to destroy it. Elsewhere Missy ran through the city, but was found by the Daleks, who realized she was a Time Lord. She was surrounded by several Dalek drones and at least one Emperor's Personal Guard, but she told the Daleks she had a "very clever idea." The decaying Daleks continued to attack, and the Doctor and Clara watched from a distance before the Doctor went back in time to save the young Davros during the Thousand Year War on Skaro to teach him about mercy. (TV: The Witch's Familiar)

The recon scout
Reconnaissance scout Daleks had more abilities than standard Daleks. One used these abilities on Earth when being hunted by the Thirteenth Doctor. (TV: Resolution)

Behind the scenes

 * Colin Baker uses the Paradigm Drone Dalek to secure a part in the 50th Anniversary Special in The Five(ish) Doctors Reboot.
 * New Paradigm Drone Dalek is one of Dalek enemies used in the Doctor Who: Legacy mobile game.