The other fantasy shared universe is Several of the King Feature Syndicate comic strip characters which first crossed over into a shared universe in the 1972 cartoon "movie"
Popeye Meets the Man Who Hated Laughter
In that cartoon, Pictured the King Feature Action-Heroes: Flash Gordon, Lothar, Mandrake, The Phantom, Steve Canyon for the first time came together to rescue the rest of the comic strip characters.
As most know them, it was revisited again when The Phantom, Mandrake, Lothar & Flash Gordon teamed up again in the 1985 Defenders of the Earth animated series.
[YT]zIpOluaTQj8[/YT]
And most recently yet again in Dynamite comics, who in 2013
secured the right to the three franchises under one roof, now naming them together as
Kings Watch
Sadly, as far as the movies rights, I believe The Phantom, Mandrake + Lothar & Flash Gordon are being developed at different studious, so a shared movie-verse is unlikely at the time.
Matthew Vaughn of King's Men fame was recently hired to direct Flash Gordon, I think he'd actually be perfect to develop the Phantom too, as well as Mandrake & Lothar, and lead them into a shared universe.
Hopefully at some point, one studio can eventually get them under one roof.