American writer and anthologist.
A contemporary and friend of H. P. Lovecraft, after Lovecraft's death he took a number of Lovecraft's unfinished stories and rewrote or finished them. In the process, he added new creatures to the Cthulhu Mythos.
He also wrote several novels about a British detective named ``Solar Pons, quite similar in many respects to Sherlock Holmes. To British eyes, the novels have a curious quality due to Derleth's never having been anywhere near London when he wrote them.