Space Ghost was renewed for a 2nd season in 1967, but in truth, the 6-part "Council of Doom" arc served a dual purpose.
These were the only new episodes of Season 2, as otherwise the season 1 episodes cycled through anew. In the course of the arc, viewers were introduced to Hanna-Barbera & CBS' freshman class of 1967--Moby Dick, Mightor, & Shazzan.
And, yes, that is Ted Cassidy as Metallus.
Gary Owens (Space Ghost) doubles as narrator:
That the series was renewed at all was an achievement unto itself. It would take 3 more years before another H-B cartoon was renewed at CBS (Scooby-Doo, of course).