Due to their gliding motion Daleks were notoriously unable to tackle stairs, which made them scary yet easily overcome under the right circumstances. An often-copied cartoon shows a flight of stairs with a sign saying "To Earth" at the top; at the foot of the stairs a Dalek says "Well, that ****s up the invasion plans". In Remembrance of the Daleks it is shown that Daleks can go up stairs after all using a sort of limited antigravity, but their awkward forms still limit their mobility in tight quarters. In a classic scene from "Destiny of the Daleks", the Doctor and companions escape from Dalek pursuers by climbing into a ceiling duct. The Doctor (Tom Baker) calls down "if you're supposed to be the superior race of the universe, why don't you try climbing after us? Bye bye!" The Daleks generally make up for their lack of mobility with overwhelming firepower.
The scriptwriter who devised them, Terry Nation[?], stated that he was inspired by watching ballet dancers in long dresses glide as if on wheels; and for many of the shows the Daleks were "played" by retired ballet dancers sitting inside the Dalek wearing black socks. He also said that the name came from a volume of a dictionary or encyclopedia who spine read "Dal - Lek". He later admitted that he had made this up as a reply to a question by a journalist and that anyone who checked out his story would have found him out. The name had in reality simply rolled off his typewriter.
Nation was pleasantly surprised to discover that in Serbo-Croatian the word "Dalek" means "far and distant thing".
Later the Daleks were seen as an analogy to the Nazis, particularly in The Dalek Invasion of Earth.
The Daleks were first introduced in December 1963 in an episode of Doctor Who called variously, "The Daleks", "The Dead Planet" or "The Mutants" (the reason for this confusion is that in the show's early years each individual episode had a different name; "The Dead Planet" and "The Mutants" are both episodes within the serial "The Daleks"). They immediately became a hit, and were featured in many subsequent serials.
Two movies starring Peter Cushing spun off from Doctor Who featured them as the main villains: Doctor Who and the Daleks, and Daleks: Invasion Earth 2150 AD. However, the movies made several changes to the original concept; for instance, Cushing's Doctor is not an alien. The movies used brand new Dalek props, based closely on the original design but with a wider range of colours. Because the special effects on the films did not run to the creation of death-rays, their Daleks' weapons emitted clouds of deadly vapour instead.
In addition to the movies, their popularity has extended to books and stage shows.
Over the twenty-six seasons of the series, the Daleks underwent a number of revisions and elaborations. In the origin story Genesis of the Daleks (1975), the creator of the Daleks was revealed to be the Kaled chief scientist Davros. Although Davros appeared to have been killed by his own creations at the end of the serial, he survived their attack in suspended animation and was later recovered from the ruins of Skaro by the Daleks seeking his help to enhance their design. Davros' continuing influence eventually led to a schism among the Daleks, with one faction following Davros' leadership (the "Renegade" Daleks) and another faction rejecting their creator to instead follow the Supreme Dalek (the "Imperial" Daleks).
Davros made his last appearance in the Doctor Who TV serial Remembrance of the Daleks simply as a head inside a large Dalek.
The Daleks were actually operated from inside by short actors who had to manipulate their eyestalks and arms, as well as flashing the lights on their heads in sync with the actors supplying their voices. Unfortunately, as well as being hot and cramped the Dalek casings also muffled external sounds, making it difficult for the operators to hear the director's commands or studio dialogue.
The Dalek cases were built in two pieces; once an operator stepped into the lower section the top would be lowered onto him. This had advantages and disadvantages. Operators were often able to eavesdrop on private conversations between people who thought the casings were empty, but the top sections were too heavy to move from inside which meant that the operators could be trapped in them if the stagehands forgot to let them out.
Early versions of the Daleks were either rolled around on castors or propelled by wheels connected to hand cranks by bicycle chains. Later versions had more efficient wheels and were simply propelled by the operators' feet. Even so, they were so heavy that when going up ramps they often had to be pushed by stagehands out of camera shot.
In scenes where many Daleks had to appear some of them would be represented by wooden replicas or even (in early black and white episodes) by life-size photographic enlargements; in scenes involving armies of Daleks models were used, with the models actually being commercially-available toy Daleks on some occasions.