- Myron Rodemus (5E), a Wererat of the Rodemus Merchant Family of Karameikos introduced in a 5E Unearthed Arcana PDF.
- Baron Ludvig Von Hendriks (5E) and a group of rebels fighting against him are mentioned in this 5E Unearthed Arcana PDF.
- Zargon (3E, 5E), detailed in Elder Evils (3E) and mentioned in Sword Coast Adventurer's Guide 5E.
- Catharandamus, originally from Palace of the Silver Princess, makes an appearance in 3rd edition's Tome of Magic. For his failures, Arik has transformed him into a ghoul.
- Dorn, High Priest of Zargon, a native of Cynidicea detailed in Elder Evils.
- Vanessa Mackelroy, a priestess of Zargon (a tiefling not native to Cynidicea; perhaps she's from Glantri or the Isle of Dawn) detailed in Elder Evils.
- Dungeon #142 also has a number of NPCs associated with Cynidicea in it, including the priestess of Zargon Neheshru, the acolyte of Madarua Ilsinian, and the half-elf Lady Vestang.
- Chag-Nuth-Thu (from Classic Play - The Book of the Planes from Mongoose Publishing), the Glorious Toad God, is a Tsathoggua-like divine toad whose power causes an inn to regularly shift between planes of existence. Your mileage may vary, but it struck me as an homage to the Temple of the Frog and the Comeback Inn from the Blackmoor setting. Dunmorgause Castle, from the same book, struck me as probably inspired in part by Castle Amber; you could use the Castle Amber map for it, though it's different in some ways.
- Rad, an Immortal of the Sphere of Energy, is detailed in Gawds and Demi-Gawds for the Hackmaster RPG.
- Mystaros, said to be a native of ancient Blackmoor who became patron of Alphatian magic-users and chief rival of Rad, is detailed in Gawds and Demi-Gawds for the Hackmaster RPG.
- Farrow the Shadowelf (Planescape)Farrow appeared in the Planescape Supplement Uncaged, Faces of Sigil and described a Shadowelf from Mystara, living in the Planescape Setting. More detailed discussion of Farrow here.
- Meredoth the Dark Lord (Ravenloft). Detailed in Ship of Horror. Later retconned (officially) as a Dark Lord hailing from the Mystaran island of Todstein. More discussion of Meredoth here.
- Captain Garvyn (Ravenloft). The ship captain from Ship of Horror. If Meredoth is from Mystara, would not also the same be true for Captain Garvyn? Detailed in Ship of Horror.
- Factol Sarin of the Harmonium (Planescape) Although Sarin may not be from Mystara, he wears a suit of Red Steel armor from the Savage Coast.
- Warduke, Strongheart the Paladin, Figgen the Halfling and the other LJN Toy characters (Greyhawk). References to these characters appear in XL1, X10 and AC2 as well as Gaz 4. However, Warduke was later retconned into a Greyhawk character with thies to the Horned Society.
- Lord Fear (Dragon Strike) is a character from the Dragon Strike Board Game and associated novels. He was also to appear in a (never published) Wildspace novel linking him to the Spelljammer Setting as well.
- Countess d'Ambreville (Freeport). She owns an upscale brothel in the city of Freeport, where she also plies her trade as an assassin.
- Alfhild the Northwoman Raider (Freeport). has escaped from her former fiancee of King Ragnar (most likely of Soderfjord) and is rumoured to be raiding the seas around Freeport. Her husband has also been reported looking for her in the region. The people of Freeport are suspcious of them both. The character is described in the supplement Denizens of Freeport (Green Ronin).
- Strahd von Zarovich (Ravenloft). Could Strahd's home realm actually be Mystara? This is highly contested, but discussed in this thread.
- Shademaw the Dragon (Feywild). Described at Wizards.com's Monster Makover.
- Ulgurshek the Draeden (The Abyss). The only known named Draeden. Draedens were first detailed in the Immortals Set (Gold Box). Ulgurshek the Draeden is detailed in Fiendish Codex I: Hordes of the Abyss (3E).
- Hyacinth the Druid (Feywild). This druid has been known to explore the Isle of Dread. This character appeared in the Lair Assault Series.
- The FSS Beagle (d20 Modern). While perhaps not a character as such, the FFS Beagle is a Mystara/Blackmoor Spaceship that also appeared in the D20 Module Foul Weather (Free download).
- Prince Prospero, a possible relative of the Wizard Prospero, author of the Poor Wizard's Alamanacs, is living in the Gothic Earth of Ravenloft's Masque of the Red Death Setting. See more here.
- Dubricus d'Ambreville (Greyhawk), a wizard undoubtedly related to the famous family of mages from Glantri. Detailed in Return to the Keep on the Borderlands.
- "Third" (Greyhawk), warrior maiden of Maruda /Madarua from Cynidicea . Detailed in Return to the Keep on the Borderlands.
- Thomas and Holga (Greyhawk)Two Assassins linked to Cathay City. Cathay (along with Vacros) is first described in M2SOLO The Riddling Minotaur. The characters are detailed in Return to the Keep on the Borderlands.
The majority of these deties first appeared in OD&D or AD&D sources first and were then used, either fully, or just their names in Mystara products. Many of them were also later used in third party material.
- Garl Glittergold
- Yeenoghu - Also known on Mystara as Ranivourus, patron of Gnolls
- Hruggek - Also known on Mystara as Bartziluth, Patron of Bugbears
- Vaprak - Also known on Mystara as Jammudaru, patron of Ogres
- Kurtulmak - Also known on Mystara as The Shining One, patron of Kobolds
- Ilneval - also known on Mystara as Karaash, patron of Orcs
- Odin - also known on Mystara as Wotan
- Thor - also known on Mystara as Donar
- Loki - also known on Mystara as Lokar
- Frey - also known on Mystara as Fredar
- Freyja - also known on Mystara as Fredara
- There's (as we all know) a line of Blackmoor products from Zeitgeist Games with Mystara references. Some of the gods of that setting are named for Mystaran Immortals: Ordana, Khoronus, etc.
The following locations have strong ties with Mystara, but have also been used with other settings such as Greyhawk and the Nentir Vale.
- The Isle of Dread (X1)
- The Keep on the Borderlands (B2)
- The Caves of Chaos (B2)
- Lost City of Cynidicea (B4)
- The FSS Beagle - See Above
- Citadel of Neversleep in the Altan Tepes Mountains.
- Hackmaster also has other "hacked" versions of Mystara modules: Quest for the Unknown, Little Keep on the Borderlands.
What do such things mean for Mystara? Can we use such third party book information on characters and locations to expand our Mystara campaigns? Could characters spending time on other worlds, eventually return to Mystara? How would their experiences there affect how they act on their return?
Non-Mystara Characters in Mystara
- Giff Captain named Blotomus (Spelljammer) - First Quest Boxed set
- Raver the Neogi (Spelljammer) - First Quest Boxed set
- Pickman the Wizard (Thunder Rift) - Possibly related to Richard Upton Pickman from H.P. Lovecraft's short story "Pickman's Model", who is said to be descendant from the Salen Witch Trials. Richard Upton Pickman gradually turns into a Ghoul. Could Thunder Rift's Pickman have visited the New World (North America) of LaTerre?