Steel Octopus

The Steel Octopus was an enemy which the Fourth Doctor recalled having defeated. (PROSE: The English Way of Death)

Behind the scenes
Among some 250,000 entries, the Steel Octopus, created by Karen Dag, was one of three winners of Blue Peter's 1967 design-a-monster-competition, along with the Aqua Man and the Hypnotron. Unlike the later Abzorbaloff, it was not featured in the Doctor Who television series, however, a prop Steel Octopus was constructed alongside the Hypnotron and the Aqua Man. (REF: The Doctors: The Archive)