Daleks

"EXTERMINATE!"

- Catchphrase of the Daleks

"Daleks are the Masters of Earth"

- Supreme Dalek

Daleks are a main enemy of the Doctor in the long-running British, sci-fi series Doctor Who. The Daleks were created by writer Terry Nation and designed by Raymond Cusick. Their main objective is to reign supreme over the Universe and destroy every other species, seeing the Doctor as "The Oncoming storm" or mortal enemy. The Daleks have become a very famous icon for Doctor Who, mainly for their catchphrase "EX-TER-MI-NATE!" They were introduced in the 1963 Doctor Who serial, The Daleks.

Origin
The Daleks originated from Skaro during a thousand tear-long war was going on between the Kaleds and Thals. They are result of a Kaled scientist named Davros experimented on his people as some are mutated by the war. In time, Davros removed the blobs of flesh of all emotions save hatred and placed them in tank-like "Mark III travel machines" partly based on the design of his wheelchair. Thus, despite the fourth incarnation of the Doctor sent to avert their creation on the Time Lords' behalf, the Daleks are born as they disposed of Davros acted on his desire for them to be ultimate lifeform while exterminating what they consider inferior.

Five centuries later, having enslaved the surviving Thals and pacified them as they are unable to leave their base of operations, the Daleks encounter the first incarnation of the Doctor when he arrives to Skaro and gives the Thals the courage to stand up and fight for their freedom.

Over the course of their encounters with the Doctor and his other incarnations, the Daleks developed time travel and evolved into an interstellar empire by the year 4000. Eventually encountering a hostile race of androids called the Movellans, the Daleks realized they were in a stalemate and decide to revive Davros to give them an advantage. However, Davros was captured and imprisoned for his crimes with the Daleks locked in combat with the Movellans until they developed a virus that targets the Daleks a century later. Though the Daleks rescued Davros to help develop a cure, their creator betrays them and later develops Imperial Dalek loyal to him. This causes a a schism among the Daleks, with one faction following Davros's leadership and another rejecting their creator to instead follow a Supreme Dalek.

The Endeavor of the Daleks
Eventually, Davros succeeds in becoming the unquestioned emperor of the Daleks as he and the Renegade Daleks appear on Earth to obtain the Hand of Omega to refine their crude time travel technology. But the Seventh Doctor rigs the hand to have Skaro's sun go supernova to wipe out the Dalek homeworld and the Imperial Dalek fleet. Though the Renegade Supreme Dalek self-destructed upon learning to be the last of its kind, Davros, escaped his flagship's destruction in an escape pod and created a new breed of Dalek that executed the Master for his crimes. These Daleks later battled the Time Lords in the Time War, in which the Doctor obliterated both them and his people.

However, some Daleks survived and escaped the Time War: a lone Dalek that was kept in a secret underground museum called the Vault along with other alien artifacts before using Rose Tyler's imprint to regenerate and having her activate his self destruct upon realizing it gained emotions, and the insane Emperor Dalek that created a more dangerous form of Dalek from human tissue by using minions like the Jagrafess. Rose stopped him by absorbing the time vortex of the TARDIS to save the ninth incarntion of the Doctor, who fought against the Emperor.

The most infamous of the Daleks were the members of the Cult of Skaro who escaped during the Time War by going into the nothingness between dimensions — the Void — taking with them a Time Lord prison, dubbed the Genesis Ark, which contained millions of Daleks.

The Daleks' Void Ship finally emerged in 21st century Earth, where it was examined by the Torchwood Institute. The path of the void ship also left a breach in spacetime that allowed the Cybermen of a parallel universe to cross over. This results in a three sided fight between the humans, Cybermen, and Daleks until the Tenth Doctor has the monster armies sucked into the void with the Cult of Skaro escaping to 1920s New York.

The End of the Daleks
Unable to create a new generation of Daleks, the Cult's leader Dalek Sec hatched a plan of evolve their species into a more adaptive race to escape extinction. The Cult of Skaro employ a man named Mr Diagoras to finishing the Empire State Building and reinforce it with Dalekanium metal while Dalek Caan, Dalek Thay and Dalek Jast were assigned to take more intelligent humans they capture to became part of the Final Experiment: converting their bodies into blank slates to be infused with Dalek DNA. With his fellow Daleks making sacrifices for their scheme, Sec follows suit by assimilating Diagoras to become a "Human Dalek" and splice his DNA into the humans through gamma radiation from the Sun.

However, as Sec begins to develop emotions and makes peace with the Doctor, Caan staged a coup that killed Sec and became the new cult leader with the intent to infuse the captured humans with pure Dalek DNA. However, the Daleks' plans fell into ruin when their Dalek army was corrupted with Time Lord DNA and Thay and Jast were killed.

The sole survivor of the Cult of Skaro, Dalek Caan terminated the Dalek-Human army by remote before the Dalek initiated an emergency temporal shift to force his way into the Time War to save Davros at the cost of his insanity and armored body. Regardless, establishing the New Dalek Empire, Darvos produces a new generation of Daleks from his flesh and uses them to enact a scheme to wipe out reality itself. But the interference of The Doctor and his companions had stopped Davros' plans, who learns that Caan engineered it so the Daleks would be destroyed forever as the Crucible explodes with all Daleks and Davros destroyed in the process.

The Return of the Daleks
However, remnants of the New Dalek Empire survived and ended up in England during World War II where they posed as weapons called "Ironsides" that are used by Winston Churchill. Awaiting for the Eleventh Doctor, the Daleks trick him to confirm them as Daleks so that can activate the Progenitor, a small capsule containing pure Dalek DNA. Though their plan was a success, the five newly created Daleks vaporize their predecessors before escaping into the future where they rebuild the Dalek race and played a role in the Doctor's sealing in the Pandorica.

Eventually, the Doctor and his companions Amy and Rory are drafted by Dalek Prime Minister and enter the Asylum of the Daleks, a planetary prison, to disable the force-field so that the Daleks could destroy the Asylum before its most dangerous occupants could escape. It was at that time that Doctor encounters Oswin Oswald, learning that she is a human converted into a Dalek yet managed to maintain herself. Helping the Doctor succeed at the cost of her life, Oswald hacked into the Daleks' psychic path-web to delete all memory of the Doctor from them.

Trivia

 * According to one of the show's writers Terry Nation, the Daleks were deliberately modeled after elements of Nazi ideology: viewing themselves as the superior lifeform and enact a relentless crusade to destroy all life they consider inferior.
 * The late comedian, Dave Allen, on his show Dave Allen At Large, had an opening skit wherein a British vicar was surprised by a Dalek disguised as a fixture in his church.
 * The Daleks also make cameo appearances in Looney Tunes Back In Action.