Other Fighting Fantasy sub-series

There have been a number of other sub-series within the Fighting Fantasy range over the years. By sub-series, I don't just mean books by the same author(s) or adventures which take place in the same setting. Something else significant (and particular) must feature within the gamebooks themselves, connecting them into a series. The following is a list of some possible sub-series, with the features that connect them highlighted:

• The 'Astragal' trilogy: Chasms of Malice, Daggers of Darkness and Fangs of Fury (by Luke Sharp). All set in southwest Khul, with different heroes, but with the recurrent character Astragal the Wizard who appears to be trying to keep a lid on chaos in this turbulent part of Titan (another recurrent character is Alkis Fearslicer).
• The 'Mandrake trilogy': Legend of the Shadow Warriors, Moonrunner and the unfortunately never written/published Blood of the Mandrake (by Stephen Hand). Set in and around Gallantaria in the Old World, featuring several recurrent sub-plots (e.g. the Mandrakes and the Kauderwelsches). It's not clear that the hero of LotSW and MR are the same individual, but they could be interpreted as such I think.
• The 'Vampire' saga: Vault of the Vampire and Revenge of the Vampire (by Keith Martin). These two books involve attempting to destroy the vampire Count Reiner Heydrich. It's not clear that the hero is the same in the two books (otherwise we'd expect to see more obvious links). Tempting though it is, there isn't really anything much to connect these two books with Jon Green's Howl of the Werewolf other than VotV and HotW being set very close to each other geographically and featuring the same kind of adventurer.
• The 'Isles of the Dawn' or 'Maior' duology: Black Vein Prophecy and The Crimson Tide, both written (at least in part) by Paul Mason, set in the Isles of the Dawn, and featuring recurrent characters, including Maior and Poo Ta. The hero cannot be the same individual in the two books (and indeed the heroes from the two books may meet).
• The 'Riddling Reaver' or 'Kallamehr' series: The Dreaming Sands (Warlock 13), The Riddling Reaver, Slaves of the Abyss and Magehunter, all written, in part at least, by Paul Mason. Warlock 13 tells us that The Dreaming Sands was written as a prelude to The Riddling Reaver. Slaves of the Abyss could conceivably follow on from TRR, but there's no sure evidence that the hero is the same; it does follow on in terms of the history of Kallamehr though (Baron Bluestone is dead and the Lady Carolina rules the city). Magehunter has an entirely different hero, but follows on chronologically (in terms of the history of Kallamehr) from SotA. All of the adventures except The Dreaming Sands feature the city Kallamehr, two of the adventures include encounters with the nightmarish Maijem-Nosoth, and all have appearances by the Riddling Reaver.
• And then of course there's Zagor. It used to be relatively simple; there was The Warlock of Firetop Mountain and then a while later Return to Firetop Mountain came along. The adventures are set 10 years apart, but both involve you entering Firetop Mountain and confronting Zagor. Titan - The Fighting Fantasy World gave us a bit of backstory, and The Trolltooth Wars complicated things slightly. But then Legend of Zagor and the Zagor Chronicles were published (and were tied in with Casket of Souls), and I no longer have a clue what the deal is with Zagor, where he came from or how old he is. I think I'll return to that problem in another post!

So I think that's the obvious sub-series within Fighting Fantasy (Sorcery!, the novels and Advanced Fighting Fantasy adventures aside of course); have I missed anything obvious?