Slyther (The Dalek Invasion of Earth)

Towards the end of the 22nd century Dalek invasion, the Dalek Supreme Controller used a Slyther to guard the Bedfordshire mines at night, where it killed and ate anything it found.

History
The Slyther broke through a window into a shack where it attacked a small group of humans consisting of Ian Chesterton, Larry Madison, Wells, and Ashton (killing the last). Ian hit the Slyther with a rock, causing it to fall down a pit to its death. (TV: The Dalek Invasion of Earth)

Behind the scenes

 * The Slyther appeared only in the fourth and fifth episodes of The Dalek Invasion of Earth, "The End of Tomorrow" and "The Waking Ally", and was played by Nick Evans — who also operated a Dalek in the same story.
 * A new Slyther costume was created for "The Waking Ally", as the production team were dissatisfied with the original version. This is why the Slyther changes appearance between the end of "The End of Tomorrow" and the beginning of "The Waking Ally".
 * The description of the Slyther in Terrance Dicks's novelisation of The Dalek Invasion of Earth as being "a vast lumpy blob of a body, powerful flailing tentacles, two tiny deep-set eyes shining with malice..." (quote, page 101) is actually that of a Mire Beast from TV: The Chase. It would appear that the BBC sent Dicks the wrong reference photograph.