The Metebelis Spiders, also known as the Eight-Legs, are the main antagonistic group in the Doctor Who story "Planet of the Spiders".
This was their only appearance on screen, although they have appeared in other media.
Some 430 years before the events of the story, a spaceship from Earth crashlanded on Metebelis Three. A colony of spiders ended up in the mountains where they were mutated by the blue crystals, which increased their mental powers and size (making them roughly the same size as a small mammal). They were able to communicate telepathically, control minds and mentally inflict pain. They came to dominate and enslave the human population, who they dubbed "Two-Legs", referring to themselves as "Eight-Legs" and forbidding the word "spider". Some humans were recruited to serve as their field guards. They fed on the flesh of human dissidents and also massacred a village who refused to pay tribute to them.
The spiders dreamed of dominating Earth but needed one last crystal, which had been removed by the Third Doctor and taken to 20th century Earth. They sent one of their number using a psychic link with a meditation circle, where it formed an alliance with the greedy human Lupton. The Doctor followed Lupton and his spider back to Metebelis Three, where he encouraged the humans to rebel, providing them with stones that deflected the spiders' mental blasts. The spiders defeated the rebellion but the Doctor insisted on giving the crystal to their giant leader, the Great One. Her attempt to use the crystal to increase her mental powers to infinity killed her, and the other spiders apparently died with her.
However, in the short story "Return of the Spiders", the Fourth Doctor and Romana encountered a group of spiders on Earth, who were preparing to breed. The Doctor destroyed the newborn spiders with a combination of fire and water. In the novel "The Eight Doctors", the Seventh Doctor encountered a group of surviving spiders on Metebelis Three but was saved by the Eighth Doctor.
In the audio plays "The Eight Truths" and "Worldwide Web", the Eighth Doctor discovered a group of spiders had taken control of a psychic group in Yorkshire and were planning to take over every being in the cosmos. They were defeated by the Doctor and the Headhunter.
- The spiders were voiced by Maureen Morris, Ysanne Churchman and Kismet Delgado.