Managing to squeeze this one in before the new series starts in a few weeks!
Shoal of the Winter Harmony
Brains with eyes… just goes to show how good Who is at taking something completely stupid and just making it work. It seems the more ridiculous the concept the better it pays off. These brains in jars were suitably menacing and provided much clearer concept and entertainment value than done of the more realistic species encountered.
The Shoal of the Winter Harmony were a race of fully intelligent central nervous systems. Able to exist independently with their own eyes and mouths the species were able to inhabit a body as their ‘brain’. They invaded planets by capturing the bodies of global leaders.