The Mad Goblin by Philip Jose Farmer
I’m seeing a lot of Philip Jose Farmer’s work come back into print, which is a good thing. The Mad Goblin is one of two parallel sequels to A Feast Unknown. This one focuses on James “Doc” Caliban (yes, based on Doc Savage), half brother of the fellow Tarzan was based on. Both are former agents of “The Nine.” A group that discovered the secret to extremely prolonged life thirty thousand years ago and has ruled the Earth from behind the scenes since then. This is adventure pulp at its finest, with Farmer paying tribute to one of his favorite fictional characters.