Spider

Spiders were a type of arachnid commonly found on Earth. They were noted for spinning webs which they used to catch prey.

Originally, spiders were small, inoffensive creatures, none growing much larger than a rat, though some species had a venomous bite that could be deadly to humans. By the 26th century, though, radiation had caused mutations, allowing them to reach much larger sizes. (PROSE: Ship of Fools) An example of this were the Eight Legs, spiders with great mental powers, who evolved on Metebelis III from spiders that survived the crash landing of a human ship. (TV: Planet of the Spiders)

K9 once encountered spiders on a planet in another dimension, partially inhabited by ex-Tellac miners. They lived alongside other Earth animals from widely varying periods of evolutionary history. Unlike most species of spider on 21st century Earth, however, these were as big as gorillas, and their webs spanned between trees. (PROSE: K9 and the Missing Planet)

Another planet was home to giant spiders which were controlled by the Master of Spiders. When he used them to attack the Second Doctor, John and Gillian, the Doctor used his ray gun to kill one spider (while shouting "Die, hideous creature... die!") and used his recorder to keep other spiders from attacking them. When the Master was defeated, the Doctor sealed the surviving spiders back in their cave. (COMIC: Master of Spiders)

Another planet was home to large spider-like creatures. The sons of Grekk, who also lived there, viewed them and all the other intelligent life forms on the planet as vermin, and had vowed to exterminate them all. When the First Doctor was imprisoned, he and the other prisoners used the webbing produced by the spiders to set a trap for the sons. (PROSE: The Sons of Grekk)

The Eleventh Doctor saw a spider on a web upon arriving at the Silurian Ark. He noted that he didn't usually see "spiders in space." (TV: Dinosaurs on a Spaceship)

On Earth, toy versions of spiders were used as Halloween decorations. The night after one Halloween, an alien possessed hundreds of toy spiders left behind in a warehouse to attack and frighten the Eleventh Doctor and Louie Rollins. (PROSE: The Night After Hallowe'en)