Voltron Middle Universe (lost unmade adaptation of animated series; dates unknown)
Voltron: Defenders of the Universe is an American re-edit of the Japanese anime series Beast King Golion. The series proved to be far more popular abroad than Golion ever was in Japan and popularized the combining giant mecha plot in America. Despite heavy censorship (nearly every character who died in Golion was 'saved' in Voltron through bits of dubbed dialogue), the series not only showed all 52 re-edited episodes of Golion, but contracted out to Toei for 20 more Golion styled episode strictly for American release. When combined with the episodes of Vehicle Voltron (itself a re-dub of another anime, Armored Fleet Dairugger XV, with dubbed-over connections between each series), this led to 125 episodes, followed by the TV Special Voltron: Fleet of Doom allowing both Voltron robots and their teams to actually meet on-screen.
But originally, Voltron was to have been a trilogy, with the then Voltron toy licensee Matchbox revealing the Vehicle Voltron being Voltron 1, Defender of the Near Universe, Lion Voltron being Voltron 3, Defender of the Far Universe and Voltron 2 being the Gladiator Voltron of the Middle Universe and plans on adapting it after Vehicle Voltron but the stellar success of the Lion Voltron series and the lukewarm reception of the Vehicles quickly caused a shift in the focus of World Events Productions that scuttled these plans and made the aforementioned 20 US exclusive episodes.
What might have been & what might exist
A third Japanese anime series, Lightspeed Electroid Albegas, also from Toei, was optioned to become the basis for this idea. It featured three robots who combined into one gigantic one. It is unknown what connection the heroes or villains of Albegas would have had to the other two teams, presuming the pattern from Lion and Vehicle Voltron was kept to. Bumper video exists of Lion and Vehicle being described as Far and Near Defenders, but Middle Universe is not by any direct reference or footage outside of the Matchbox toyline.
Original Voltron series writer Marc Handler stated that he started working on the adaptation of Albegas into Voltron, but he had not yet been assigned to do so. WEP never officially started commissioning the adaptation. Handler has not released any details of that work.
- Let's Voltron podcast episode 9: Original Series Writer Marc Handler (Part 1)