Lake Monster

The Lake Monsters were a species of flat, tentacled, predatory mutants with glowing eyes who existed on Skaro.

One Lake Monster lay deep in the Lake of Mutations and killed Elyon by pulling him beneath the water. (TV: "The Expedition")

Behind the scenes

 * In the webcast A return to Skaro for the First Doctor... (which is not currently considered a valid source by this wiki), a Lake Monster in the petrified jungle was shown to be disturbed by the return of the Doctor's TARDIS (as per Return to Skaro).