I'm not one to thread-shame, but was this worth asking the Era community instead of checking out a few wikis? Are we just checking to see if
Slayven is online?
I'll throw something into the pot though.
Even though Shuma first appeared in Marvel Comics as a Dr. Strange adversary - his name was actually taken from the writings of Robert E. Howard. A name you might recognize as the creator of Conan the Barbarian. This makes Shuma Gorath Lovecraftian by proxy - since Howard and Lovecraft were pen pals and often shared ideas.
Shuma is actually one of the few Marvel creations to appear in canon during Marvel's version of the Hyborion Age. Here's our favorite squid boy looking extra fiesty when he was summoned near Conan's homeland of Cimmeria
Other villains that fought both Conan and the modern Marvel Universe include evil sorceror Kulan Gath - infamous for once transforming NYC into a version of the Hyborion Age (in an earlier apparance Mary Jane is possessed by the spirit of Red Sonja and helps Spider-Man beat Kulan Gath, Gath gets his revenge by killing Spider-Man after he transforms NYC - though he gets better).
And Varnae the First Vampire. Yup, he's actually the very first Vampire created by the Darkhold. He chose Dracula as his successor.