Harold Warner Munn (November 5, 1903 – January 10, 1981) was an American writer of fantasy, horror and poetry,^[1] best remembered for his early stories in Weird Tales. He was an early friend and associate of authors H. P. Lovecraft and Seabury Quinn. He has been described by fellow author Jessica Amanda Salmonson, who interviewed him during 1978, as "the ultimate gentleman" and "a gentle, calm, warm, and good friend." He was known for his intricate plotting and the careful research that he did for his stories, a habit he traced back to two mistakes made when he wrote his early story "The City of Spiders".

A resurgence of interest in his work occurred during the 1970s due to its appearance in the Ballantine Adult Fantasy series and the successor fantasy series published with the imprint of Del Rey Books.

In addition to writing, Munn collected books and classic pulp magazines, including Air Wonder Stories, Amazing Stories, Astounding and other science fiction titles, along with Argosy, Argosy All Story, Cavalier, Weird Tales (to the end of the Wright publication series), and others. Also in his library were self-manufactured^{[clarification needed]} books consisting of serialized stories extracted from magazines, notably works by George Allan England such as "Darkness and Dawn". About three fourths of his collection was ruined by exposure to weather during a relocation and had to be destroyed.

During his last years Munn lived in Tacoma, Washington in a house he had built himself. He did his writing either in his living room or in the attic room that constituted his library. During this time he was working on an additional volume of the Merlin series to be called The Sword of Merlin, which he did not live to finish. He was befriended at this time by the young writer W. H. Pugmire, who was influenced by Munn's work.

Munn was a major early contributor to the pulp magazine Weird Tales during the 1920s and 1930s, with the editorship of Farnsworth Wright. Munn's first, "The Werewolf of Ponkert" (1925 WT) arose from a comment by H.P. Lovecraft suggesting a story written from the werewolf's point of view.^[1] Munn's resulting tales became the first of a series, "The Tales of the Master". The series included a serial, "The Werewolf's Daughter" (1928 WT) and this and the initial story appeared as The Werewolf of Ponkert (1958). Munn later continued the Werewolf Clan stories; these dealt with the descendants of the werewolf in the first story. The plots of the Werewolf Clan tales revolved between the struggle between the titular family and "The Master", a supernatural villain that Munn based on Charles Maturin's Melmoth the Wanderer.^[1] When the change of editors of the magazine from Farnsworth Wright to Dorothy McIlwraith; McIlwraith used different writers, Munn's major market was eliminated. Munn later reworked the other stories and added extensively to the series, most of these tales appearing initially in Robert Weinberg's "Lost Fantasies" series, and then in book form as Tales of the Werewolf Clan #1: In the Tomb of the Bishop (1979) and Tales of the Werewolf Clan #2: The Master Goes Home (1979).^[2]

The two series of works for which he is known best, his Merlin saga and the Tales of the Werewolf Clan, were both started during the Weird Tales period. King of the World’s Edge, the first Merlin novel, was written as early as 1925. On publication (Weird Tales, 1936) it was compared favorably to the stories of Robert E. Howard, of whose fiction Munn confessed to being a great admirer. The novel starts in the last days of King Arthur, and follows the adventures of Myrdhinn (Merlin) and a Roman centurion, who leave Britain for new lands to the West, and find themselves in the kingdom of the Aztecs.

After Weird Tales ceased publishing his work, Munn generally did not seek new outlets. he devoted to his time to family duties for many years and worked in various trades from sawmill operator to ice cream salesman. It was not until he lost a knee cap in one of these jobs that Munn returned to full-time writing around 1965.

With the exception of the 1980 epic historical novel, The Lost Legion, his post-Weird Tales output was minor, most of it either self-published in small press editions or issued haphazardly by publishers who sought him. While he had already completed The Ship from Atlantis, the second installment of the Merlin Saga, in 1941, it was only published 26 years later, when Donald A. Wollheim contracted to publish King of the World's Edge in book form and also accepted the sequel. The Ship from Atlantis follows the further adventures of Gwalchmai, who sets out for Rome but becomes lost in the Sargasso Sea and encounters a survivor from Atlantis. These two novels, later combined under the title Merlin's Godson (omnibus 1976), are a precursor to Munn's magnum opus, Merlin's Ring (1974).

The publication of his last great work of fantasy, Merlin's Ring (third of the series), was also the result of a publisher seeking him. Reprising Wollheim's role, Lin Carter, editor of the Ballantine Adult Fantasy series, learned of it while enquiring about the availability of the first two Merlin books. In the event, it was issued by Ballantine Books soon after the end of Carter's connection with the publisher, in the interregnum between the Adult Fantasy series and Ballantine's new Del Rey Books fantasy series. Merlin's Ring explores the Atlantean and Arthurian influences down through history to the time of Joan of Arc. Del Rey later completed Carter's original intention by reissuing both of the first two books in a single volume with the title of Merlin's Godson.

Munn was fascinated by Joan of Arc and wrote an extensive narrative poem about her, The Banner of Joan (1975). Although essentially nonfantastic - other than in Joan's spirit-driven zeal - the poem may be seen as an epilogue to the Merlin sequence.

Robert E. Weinberg was responsible for the revival and completion of the Werewolf Clan stories when he expressed an interest in reprinting them in his periodical Lost Fantasies. Munn had originally written eight werewolf stories for Weird Tales before its change of editorship; he now wrote two more to fill gaps in the sequence, and the entire series appeared in three parts in Lost Fantasies, nos. 4–6, 1976–77, as "Ten Tales of the Werewolf Clan." Afterward Munn wrote and self-published three additional stories to finish the series. The complete series was issued by Donald M. Grant, Publisher, Inc. as Tales of the Werewolf Clan, Volumes 1-2 (1979–80).

Some of Munn's late horror stories were published in such anthology series as Daw Books’ The Year's Best Horror Stories. After his retirement he produced a number of stories for small-press magazine, especially Weirdbook. He developed a new sequence that sought to link Lovecraft's Cthulhu Mythos stories with an Arthur Machen-esque ancient race of Pictish fairies. The published tales are "The Merlin Stone" (1977), "The Stairway to the Sea", and "The Wandered of the Waters", all in Weirdbook. Every birthday and Christmas from 1974 to 1980, Munn issued a booklet as gift for friends. These were usually poetry, but several were short fantasies.

The Lost Legion is Munn's only other published novel. It is a sister to King of the World's Edge but set 400 years earlier at the time of Caligula.

H. Warner Munn was a Founding Syndic [with John Charles Moran, Don Herron, and Donald Sidney-Fryer] of The F. Marion Crawford Memorial Society [Nashville] in 1975. He contributed to the first three numbers of its annual review The Romantist (1977–1979), and also to Number 4-5 (1980–1981) that was an In Memoriam tribute to him.