Spider Dalek

Spider Daleks, or Spider-Daleks, were a Dalek variant known for their strange design and heightened mobility. Various accounts offered different versions and histories of the Spiders, with some indicating them to be a normal yet obscure model (PROSE: War of the Daleks, et al.) and others indicating they were never made in normal reality (PROSE: Father of the Daleks) and instead originated from other versions of history. (COMIC: Fire and Brimstone, PROSE: Engines of War)

Description
Several appearances and variations of the Spider Daleks existed.

Some accounts depicted Spider Daleks as having a casing which would separate into many legs bonded with an exposed Dalek mutant resembling large spider or humanoid insect, (PROSE: The Chronicles of Doctor Who?, COMIC: Fire and Brimstone) although these accounts were connected to another reality. (COMIC: Fire and Brimstone, PROSE: The Infinity Doctors)

Other accounts featured casings which did not expose the inner mutant, instead having legs connected to bodies similar to most Daleks. The eight-legged Spider Daleks' casings were slightly larger and more maneuverable than normal Dalek drones, but more vulnerable at their joints. Giant-sized versions, known as Striders, were ten times larger than the standard Spider Dalek. (PROSE: War of the Daleks) Another model had just three legs. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) During the Last Great Time War, the Spider Daleks of the Skaro Degradations had red and black egg-shaped bodies with three legs. (PROSE: Engines of War)

Creation
The Spider Daleks were one of Davros' "stranger designs" from an early point in Dalek history. While several accounts indicated these Daleks were successfully created, (PROSE: War of the Daleks,  The Astounding Untold History of the Greatest Enemies of the Universe) one indicated Davros never got the design to work. (PROSE: Father of the Daleks)

The Spider Daleks who fought in the Last Great Time War came from an alternate history of the creation of the Daleks created by Time Lord attempts to avert the Daleks' genesis. (PROSE: Engines of War) Similarly, in Barusa's universe, Davros created the spider-like Daleks after the war which devastated Skaro. The Doctor tried to avert their genesis, but decided not to for moral reasons. The Master then killed Davros and took control of the Daleks. (PROSE: The Chronicles of Doctor Who?)

Activity in the universe
An Imperial Earth Spydrone once captured an aerial photograph of a Dalek invasion fleet. A three-legged Spider Dalek was visible alongside the numerous Grey Daleks. This reportedly puzzled military analysts, as Spider Daleks had never been observed to be deployed alongside normal Dalek forces up until that point. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

At one point, the Spiders re-emerged after being absent for several centuries. After his resurrection and participation in the Imperial-Renegade Dalek Civil War, Davros noticed Spider Daleks among the Dalek Prime's forces. He was pleased to see that they were still in existence. The Spiders were Davros' last loyal creations, and it was a Spider who performed Davros' apparent execution, leaving the possibility that Davros was not actually executed. (PROSE: War of the Daleks) After these events, Sam Jones once relived a memory of seeing Spider-Daleks. (PROSE: Placebo Effect)

Prior to the outbreak of the Last Great Time War, Davros's command ship had an "arachnid chassis" in its archive of Dalek casings dating back to Davros' earliest experiments. (PROSE: Father of the Daleks)

Last Great Time War
Spider Daleks were combatants among the shifting timelines of the Last Great Time War, with one three-legged model prevalent as part of the Skaro Degradations. (PROSE: Engines of War)

The Neverwhen, which shifted a species back and forth along evolutionary potentials, once evolved a group of regular Daleks into "the spider-forms of the Fifth Skaro Devastation". (AUDIO: The Neverwhen)

Cinder frequently fought Spider Daleks on Moldox. (PROSE: Engines of War)

Production history
The Spider Daleks originated as a proposed redesign for the Daleks in a rebooted Doctor Who TV series that would have followed from the Leekley Bible. An early document from the initial development, Skaro - The Dead Planet: A brief history of the Daleks, shows that Philip Segal (who consulted The Terrestrial Index) intended on some level for the Spiders to fit into pre-existing Dalek continuity, specifically at a point 300 years after Davros settled on Necros but before the events of The Chase. However, Leekley was more interested in retelling Genesis of the Daleks, with the Spiders taking the role of Davros' original Daleks in The Chronicles of Doctor Who? and Fathers and Brothers.

The Spider redesign was intended to take full advantage of the then-new technology of CGI. Concept art depicted these creatures as having six-legged, adaptive casings, from which their mutant controller could emerge, wielding claws and lethal weaponry. A brief screen test of these new all-CGI Daleks was broadcast on television as a trailer of sorts, early into the development of what ultimately become the Doctor Who TV movie; it was later released on DVD alongside the TV movie itself.

The Spider design was dropped for the revival next iteration, Robert deLaurentis's The Time of My Life, replaced by Daleks in humanoid exoskeletons which could take the appearance of police officers, inspired by The Terminator. Finally for the version of the TV Movie which actually produced, Segal initially wanted to use his revamped Daleks in the opening, but the opening was cut down for budget reasons. (Doctor Who: Regeneration) In Doctor Who, the Daleks executing in the prologue are heard but emphatically not seen, and they would be interpreted as more conventional Daleks by later content (such as Flashbacks and Master!).

Continued spread
The idea of Spider Daleks continued to spread. Gary Gillatt, as editor of Doctor Who Magazine, was allowed access to the production of the TV Movie, and he used this experience to advise the Magazine's Eighth Doctor comic stories. The storyline Fire and Brimstone started production in August 1996, and in its final form featured cameos from parallel universe Daleks based on a specific Spider-Dalek illustration from the Leekley Bible. This illustration was the least humanoid of the Amblin concept art and was not included in Doctor Who: Regeneration, suggesting it would not have been the Spiders' appearance in a produced Leekley series.

In early 1997, the book The Nth Doctor made public the unproduced planned for the Spider-Daleks, but did not include any images, leading to a general perception of the Spiders which skewed more towards the iconic Dalek design. John Peel would depict Spider-Daleks in War of the Daleks as being much like other models, loosely describing their appearance with the implication that their main distinguishing feature was their eight legs. Doctor Who: Regeneration publicly published various illustrations of the Leekley Spiders in 2000, but the general imagination of the Spiders had already shifted from its original vision. For example, DWMSE 5 featured a Daryl Joyce painting accompanying a discussion on the TV Movie's predecessors which had a new depiction of the Spiders based on the iconic Dalek look. Spiders with elements of this design would later appear in Engines of War and  The Astounding Untold History of the Greatest Enemies of the Universe.

Spider Dalek, based off their appearance in Engines of War, is one of Dalek enemies used in the Doctor Who: Legacy mobile game.