Has this happened to you? You've Googled "herculoids", and start browsing websites that purport to have information about The Herculoids. From professional repositories of television history to small one-or-two page fan sites (maybe that's how you ran across this blog!) And when you reach the inevitable descriptions of the cast, you see the leader of the Herculoids referred to as… "King Zandor."
And if you're like me, your reaction is always "King" Zandor?? WTF?!
Because I certainly don't remember Zandor ever being referred to as "king" during the original series. (There's one reference to Zandor's "rule over this planet" in the first episode, "The Beaked People", but none since then.) And yet, site after site will add this title to Zandor's name (usually because they've simply regurgitated the info they picked up from another website). Some even take it a step farther, referring to Zandor's wife and son as "Queen Tara"* and "Prince Dorno".
But what are they supposedly the "king" and "queen" of? The whole planet of Amzot? If so, wouldn't you expect their living quarters to be a little more, shall we say, substantial? That weird-looking tree (or whatever that is) shows absolutely no sleeping quarters, no kitchen, no pantry… or, most important of all, no office space in which to conduct the official Royal Business of whatever it is they're supposed to be rulers of.
(Although you do have to admit that Zandor certainly looks the part of king of a jungle planet. Tall, muscular, red-haired and square-jawed, with that commanding Mike Road voice. So masculine he can make a Wonder Woman tiara look macho!)
Now, it can easily be inferred from the original episodes that Zandor and Tara (and, perhaps to a lesser extent Dorno**) are personages of some importance: the peace-loving races of Amzot come to The Big Z for protection from invaders (as happened in "The Beaked People" and "The Raider Apes"); and the warlike nations want Zandor and Co. out of the way, because they know he and the rest of the Herculoids are not gonna just stand by while freedom is at risk!
Even the extraterrestrial invaders will often state the explicit goal of eliminating Zandor before putting their plans for invasion and pillage into motion; seems Zandor's reputation has spread to other solar systems.
So it's fair to assume that the Herculoids are the protectors (unofficially, at least) of Freedom and Justice on Amzot. But that wouldn't require Zandor or Tara to be royalty.
Which still leaves the question: where did this "King Zandor" stuff come from? My guess: probably an off-hand reference from a poorly-vetted press kit promoting the original run… I can easily believe that the promo materials might have been produced by staffers who weren't familiar with the show they were promoting, and couldn't be bothered to find out. (Especially if the prevailing attitude is "it's just a damn kids' show, who cares if it's accurate?")
*or worse, "Queen Tarra" (with the incorrect excess "r")!
**or "Doorknob", as a commenter at my deviantART site once referred to him, which I thought was hilarious!