Proving that Evil is an equal-opportunity employer...
...here's the first Black villainess in her premiere appearance in Fox's one-shot All Top Comics (1944).
In the early Golden Age, before superheroes and heroines domianated the market, publishers experimented with all types of strips to see what sold best.
Following the precident of pulp magazines, comics were filled with everything from detectives to pirates to spacemen.
One of the genres was the "villain" series where the bad guy/gal was the lead, and the hero (or heroes) were the secondary characters!
Fox Comics, in particular, pushed this concept with a villain/villainess strip in almost every one of their anthologies.
Since the Sorceress of Zoom strip proved fairly popular, Fox decided to try another "bad girl" strip, but made it different by a) setting it in the jungle, and b) making the villainess Black!
However, response to this story must not have been positive, since, when Merciless next appeared later that year in another one-shot anthology, All Your Comics, not only was the series now set in the Arctic (Yes, you read that right, the Arctic), the Sorceress was White...
...and would remain that way for the remainder of her brief run.
BTW, both the writers and artists of all her appearances are unknown.