I just remembered that Karl Edward Wagner also wrote a Bran Mak Morn pastiche titled Legion from the Shadows, a sequel to REH's Worms in the Earth.
If you can find them, the novels featuring Cormac mac Art and Wulfhere Skull-Splitter (two characters who appeared in a few REH stories, then were spun off into a series of their own written by Andrew Offutt and co-author Keith Taylor.
The stories concern an exiled Irish warrior who teams up with a Viking crew headed by a fierce Danish reaver. They hobnob across the European world, encountering monsters, magic, and evil. The novels were:
Tigers of the Sea (by REH, where they first appeared)
The Mists of Doom (a prequel to the series, published fourth)
The Tower of Death (with Keith Taylor)
When Death Birds Fly (with Keith Taylor)
Sword of the Gael
The Undying Wizard
The Sign of the Moonbow
Keith Taylor then went and wrote his own novel, Bard, which spun into a series of its own. I think he gave up after Bard IV (not the most original titles), but I was living overseas and would have missed it on the stands.
Taylor's series concerned an exiled Irish bard who teams up with a Viking crew headed by a fierce Danish reaver. They hobnob across the European world, encountering monsters, magic, and evil. The major difference was that the Viking was a woman, and they were lovers.
My guess is that the Bard series was spawned when writing the two Cormac/Wulfhere novels, Taylor thought "This would be much better if the Viking was a hot woman, and they were sleeping together!"
There were some other differences, such as in Howard/Offut's novels, Cormac had black hair and Wulfhere was red-headed, while in Taylor's, the bard Felimid mac Fal was a redhead and his lady was Gudrun Blackhair.
Otherwise, I think they were mostly interchangeable.
Note that these aren't to be confused with David Drake's novel The Dragon Lord, which has an exiled Irish warrior (Mael mac Ronan) and his huge Danish friend (Starkad) encountering King Arthur as they hobnob across Europe and fight a huge monster (a dragon).
Okay, I'm being a bit sarcastic there. Drake's book was, I gather, originally written as a Cormac/Wulfhere novel and had the serial numbers filed off when there was some problem with the publisher or the rights. Not sure which, but I remember reading that it had been Howard's heroes originally, so similarity is to be expected.
Though none of the above-mentioned books is particularly great, they are all a lot of fun, of the category I'd call "rainy Sunday afternoon" reading. I had long since lost these books, but found the whole of the Cormac mac Art series at a used bookstore for under $10.
If someone were to do a proper Dark Ages Europe RPG, I'd run a Cormac/Wulfhere-style campaign in a heartbeat.
