Wikipedia
Mysteron
The Mysterons are a fictional race of extraterrestrials. They are the remnants of the original Mysteron race, extraterrestrial life forms that originated in a galaxy other than the Milky Way and maintained their colony on Mars. They appear in the British science-fiction Supermarionation television series Captain Scarlet and the Mysterons (1967–68) and Gerry Anderson's New Captain Scarlet (2005), symbolised by ubiquitous projected green rings and the deep bass voice of their human convert, Captain Black.