Copyright and Trademark
The name Kull and the names of Robert E. Howard's other principal characters are trademarked by Paradox Entertainment of Stockholm, Sweden, through its US subsidiary Paradox Entertainment Inc. Paradox also holds copyrights on the stories written by other authors under license from Kull Productions Inc.
The Australian site of Project Gutenberg has many Robert E. Howard stories, including several Kull stories. This indicates that, in their opinion, the stories are free from copyright and may be used by anyone, at least under Australian law.
Subsequent stories written by other authors are subject to the copyright laws of the relevant time.
Read more about this topic: Kull Of Atlantis