Conan may be King among the sword and sorcery cognoscenti but there among those barbarians was Lin Carter's Thongor. Forging a style of myriad elements, predominantly of Robert E. Howard, Edgar Rice Burroughs, and H.P. Lovecraft, Carter's series ran for six novels between 1965-1970. Carter, along with L. Sprague De Camp, were responsible for releasing nearly a dozen of Howard's Conan novels through Lancer Books, an American publisher. The two men also created some controversy for themselves by finishing, or even rewriting portions of Howard's works. Around the time of these Lancer Conan compilations, Carter had begun work on his first Thongor novel, 'The Wizard of Lemuria'; and later in an expanded reissue as 'Thongor and the Wizard of Lemuria'.
Around 1970, Carter was reported to have been involved in a deal to bring the Conan property off the printed page and onto the big screen. Milton Subotsky (co-owner of Amicus Productions), anxious to dabble in Fantasy films, was eager to translate Howard's works into a motion picture. Some sources state he became interested in obtaining the rights to Conan as early as 1968. However in 1973, the publishing company handling the Conan paperbacks (Lancer Books) filed for bankruptcy entangling all rights in a pool of lawsuits; some of which were levied against the company for failure to keep the books in circulation -- so this early Conan deal failed to formulate. Supposedly, the quotient of sex and violence in Howard's works contributed to Subotsky losing interest in wrangling the rights to Conan; another option were the less gruesome Thongor stories of Lin Carter. While he was determined to make a sword and sorcery picture, there was one man Subotsky had envisioned as a barbarian of cinematic sorts.
Dave Prowse, Darth Vader himself, stated in his
autobiography that the Amicus co-owner approached him to play Conan,
even though the bodybuilder, actor, and Green Cross Code Man disliked the books upon reading a portion of one of them. As fate would have it, a few years later, Prowse had lunch with Ed Summer (associate producer on CONAN THE BARBARIAN [1982]) to discuss the possibility of him playing the role of Conan the Cimmerian. Not long after, the paths of Prowse and Subotsky would cross once more in regards to sword and sorcery.
After his dissolution with his Amicus partner Max J. Rosenberg in 1975, Milton Subotsky set up Sword and Sorcery Productions, Ltd. built around mounting such a fantasy picture. In their short history, a good many projects went unrealized including a theatrical version of The Incredible Hulk, and The Micronauts. Among these unmade projects was Thongor in the Valley of Demons. Having secured the rights to Lin Carter's character, Subotsky wrote a script based on Carter's inaugural Thongor novel from 1965, 'The Wizard of Lemuria'. Additionally, a nine issue series of Thongor adventures appeared in Marvel Comics Creatures On the Loose line beginning with issue #22 in March of 1973 and ending in May of 1974.
The plot of the Thongor motion picture concerned Thongor and the wizard Sharajsha attempting to thwart world domination by the Dragon Kings via the resurrection of their God. Filled with monsters and elements bordering on science fiction, it was described by talent agent Duncan Heath as a "space-horror film". Among the intended highlights were giant flying spiders, giant snakes, magical swords and stones, a metal boat that flies, druids, princesses, and the Lizard-Hawks. These are just a few things to be visualized in what was an awfully ambitious endeavor. In hindsight, it's difficult to imagine so much being crammed into what was likely to be a moderately low budget picture at best. Subotsky was so enthusiastic over the property, Thongor was envisioned as a trilogy. The production was slated to begin shooting in the summer of 1978, but through this time, there were doubts that Thongor and the Valley of Demons would ever get off the ground at all.
In 1976 the enterprising producer approached Dave Prowse for the second time, but now regarding the title character of Thongor. But earlier that year, Prowse got an offer he couldn't refuse from George Lucas -- his choice of either Chewbacca or Darth Vader in this little film called STAR WARS (1977). And as we all know by now, Prowse chose the Dark Side of the Force. Flash forward to 1978 and Thongor and the Valley of Demons remained uncast. With the film still on course it was decided that stop-motion animation would be used to bring the numerous monstrosities to life.
Modeler Tony McVey (SINBAD & THE EYE OF THE TIGER, SUPERMAN, RETURN OF THE JEDI) built some early models of the Lizard-Hawks (see insert) with the actual animation being handled by Barry Leith, animator of British kids show THE WOMBLES (1975). Tony Pratt (HELL IN THE PACIFIC, THE LAST GRENADE) was the art director while Harley Cokliss (WARLORDS OF THE 21ST CENTURY, BLACK MOON RISING) was on board as director. With storyboards, a presentation book of artwork on the characters in the proposed film (see above), and models being built, Subotsky and his co-producer Andrew Donally planned to begin shooting in June of 1978 and having it all tied up by June of the following year. The only problem was financing. 
United Artists was alleged to foot the bill, but pulled out. The once thriving company was on shaky ground at the close of the decade, and this particular property was likely viewed as a risky endeavor. Stop-motion animation was a time-consuming process, and the number of monsters intended for this picture was unusually high. MGM (who ended up absorbing UA in 1981) had the $15 million CLASH OF THE TITANS (1981) in production at this time, not to mention it had been on the fast track since 1977 and had Ray Harryhausen's involvement, a high profile commodity where the art of stop-motion was concerned. Meanwhile, Columbia had lost interest in the Fantasy genre, and Universal's CONAN THE BARBARIAN (1982) was in motion; so Thongor in the Valley of the Demons was stalled indefinitely. The heart of the auspicious producer was definitely in the right place, though. Had this first Thongor picture went before the cameras, the first sequel was to have been titled 'Thongor in the City of Sorcerers'.Subotsky's Sword and Sorcery Productions, Ltd. did get a few films made before dissolving in 1980 such as DOMINIQUE (1979), the television mini-series co-production THE MARTIAN CHRONICLES (1980), and the anthology THE MONSTER CLUB (1981).
In 2001, the rights to the Thongor property were again picked up, this time from American World Pictures with that company's CEO Mark L. Lester (TRUCK STOP WOMEN, CLASS OF 1984, COMMANDO) attached as director for a 2002 release, but have thus far produced no Thongorian results. The company makes a lot of DTV monster movies and exploitation fare like SAND SHARKS (2011), SINBAD AND THE MINOTAUR (2011), and DRAGON WASPS (2012).
Much like Howard before him, Lin Carter left behind some unfinished Thongor business after his death in 1988. However, unlike Carter's and De Camp's editorial expansion of the Conan universe, no one has yet to implement the same practice with Thongor; or actually make the movie of the Valkarthian barbarian.