August Derleth

August Derleth is widely recognized for his significant contributions to the Cthulhu Mythos, expanding on H.P. Lovecraft's universe. He also founded Arkham House, a publishing company dedicated to preserving and publishing works of fantasy and horror.

August Derleth occasionally used the pseudonym Stephen Grendon for some of his horror and weird fiction stories.

For readers interested in his detective fiction, starting with the Solar Pons series is a good entry point. If you prefer his contributions to cosmic horror, exploring his Cthulhu Mythos stories would be appropriate.