Slyther

From TARDIS Index File, the free Doctor Who reference.

Slythers were large, tentacled blob-like creatures native to Skaro. During the 22nd century Dalek invasion of Earth, the Black Dalek used a Slyther to guard the Bedfordshire mines at night, where it killed and ate anything it found. After it attacked a small group of humans consisting of Ian Chesterton, Larry Madison, Wells, and Ashton (killing the latter), Ian hit it with a rock, causing it to fall down a pit to its death. (DW: The Dalek Invasion of Earth)

The Daleks used Slythers during their assault on Lan Beta. (NA: Parasite)

Aliens and Enemies of Season 2

Planet of Giants: Forester  • Smithers The Dalek Invasion of Earth: Robomen  • Daleks  • Slyther  • Black Dalek  • Dalek Saucer Commander The Rescue: Sand Beast  • Bennett/Koquillion  • Didonians   The Romans: Nero  • Poppaea  • Didius  • Sevcheria  • Locusta  • AscarisThe Web Planet: Zarbi  • Menoptera  • Larvae guns  • Optera  • Animus   The Crusade: El Akir  • Saphadin  • Thatcher  • Fatima The Space Museum: Moroks  • Lobos  • Xerons  • Daleks The Chase: Daleks  • Supreme Dalek  • Aridians  • Mire Beast  • Frankenstein's Monster robot  • Dracula robot  • Grey Lady  • Gubbage Cones  • Robot Dr Who  • Mechanoids   The Time Meddler: The Monk  • Ulf  • Sven  • Gunnar the Giant