Elliott O'Donnell (27 February 1872 – 8 May 1965) was an author known primarily for his books about ghosts. He claimed to have seen a ghost, described as an elemental figure covered with spots, when he was five years old. He also claimed to have been strangled by a mysterious phantom in Dublin (however, no permanent effect would seem to have been suffered).
He was born in Clifton, the son of Irishman Reverend Henry O'Donnell (1827–1873) and Englishwoman Elizabeth Mousley (née Harrison); he had three older siblings, Henry O'Donnell, Helena O'Donnell and Petronella O'Donnell. After the birth of his fourth child the Rev. Henry O'Donnell travelled to Abyssinia while awaiting preferment to a new parish. Here he was said to have been attacked by a gang and robbed and murdered. Elliott O'Donnell claimed descent from Irish chieftains of ancient times, including Niall of the Nine Hostages (the King Arthur of Irish folklore)  and Red Hugh, who fought the English in the sixteenth century. O'Donnell was educated at Clifton College in Bristol, England, and later at Queen's Service Academy, Dublin, Ireland.
After originally intending to take his entry exams at Sandhurst with a view to joining the Royal Irish Constabulary (RIC), he later became a ghost hunter, but first he travelled in United States, working on a range in Oregon and becoming a policeman during the Chicago Railway Strike of 1894. Returning to England on the SS Elbe, he worked as a schoolmaster and trained for the theatre at the Henry Neville Studio, Oxford Street. In 1905 he married Ada O'Donnell (1870–1937) and served in the British army in World War I, later acting on stage and in movies.
His first book, written in his spare time, was a psychic thriller titled For Satan's Sake (1904). From this point onward, he became a writer. He wrote several popular novels, including an occult fantasy, The Sorcery Club (1912) but specialised in what were claimed as true stories of ghosts and hauntings. These were immensely popular, but his flamboyant style and amazing stories suggest that he embroidered fact with a romantic flair for fiction. O'Donnell wrote material for numerous magazines, including Hutchinson Story Magazine, The Novel Magazine, The Idler, Weekly Tale-Teller, Hutchinson's Mystery-Story Magazine, Pearson's Magazine, Lilliput and Weird Tales.
As he became known as an authority on the supernatural, he was called upon as a ghost hunter. He also lectured and broadcast (radio and television) on the paranormal in Britain and the United States. In addition to his more than 50 books, he wrote scores of articles and stories for national newspapers and magazines. He claimed "I have investigated, sometimes alone, and sometimes with other people and the press, many cases of reputed hauntings. I believe in ghosts but am not a spiritualist."
Many of O'Donnell's books possess autobiographical sections in which he reveals a desperate struggle to escape early poverty (such as the plight of the three protagonists at the beginning of 'The Sorcery Club') and scrape acquaintance with the wealthy and the influential. These revelations, coupled with both his employment of actors such as C. Aubrey Smith to help stage hauntings, and the fact that he left no notes relating to his studies after his death, suggest that he embellished or perhaps even invented many of his supposed experiences. This is borne out by the fact that virtually every reference book in the field of supernatural fiction accords O'Donnell the status as a fiction writer. Certainly he was never approached by, nor worked with, the Society for Psychical Research. However, O'Donnell once spent a night at St. Nicholas Church, Brockley Combe with Everard Feilding, an investigator from the Society for Psychical Research.
- For Satan's Sake (1904)
- Unknown Depths (1905)
- Some Haunted Houses (1908)
- Haunted Houses of London (1909)
- Reminiscences of Mrs.E. M. Ward (1910)
- Byways of Ghostland (1911)
- The Meaning of Dreams (1911)
- Scottish Ghost Stories (1912)
- The Sorcery Club (1912)
- Werewolves (1912)
- Animal Ghosts (1913)
- Ghostly Phenomena (1913)
- Haunted Highways and Byways (1914)
- The Irish Abroad (1915)
- Twenty Years' Experience as a Ghost Hunter (1916)
- The Haunted Man (1917)
- Spiritualism Explained (1917)
- Fortunes (1918)
- Haunted Places in England (1919)
- Menace of Spiritualism (1920)
- More Haunted Houses of London (1920)
- Ghosts, Helpful and Harmful (1924)
- The Banshee (1907)
- Strange Disappearances (1927)
- Strange Sea Mysteries (1926)
- Confessions of a Ghost Hunter (1928)
- Great Thames Mysteries (1929)
- Famous Curses (1929)
- Fatal Kisses (1929)
- The Boys' Book of Sea Mysteries (1930) Dodd, Mead & Company
- Rooms of Mystery (1931) London: Philip Allan & Co. Ltd.
- Ghosts of London (1932)
- The Devil in the Pulpit (1932)
- Family Ghosts (1934)
- Strange Cults & Secret Societies of Modern London (1934)
- Spookerisms; Twenty-five Weird Happenings (1936)
- Haunted Churches (1939)
- Ghosts with a Purpose (1952)
- Dead Riders (1953)
- Dangerous Ghosts (1954)
- Phantoms of the Night (1956)
- Haunted Waters, and Trees of Ghostly Dread (1958)
- The Unlucky Theatre
- Haunted Britain
- England & Wales, Free BMD Birth Index, 1837–1915 for Elliott O'Donnell – Ancestry.com – pay to view
- Elliott O'Donnell in the 1911 England Census – Ancestry.com – pay to view
- John Wilson Foster, Irish Novels 1890–1940: New Bearings in Culture and Fiction. Oxford University Press, 2008 (p. 367-71)
- Foster, p. 29.
- Elliot O'Donnell,"The Haunted Wood of Adoure", Weird Tales, July 1930. Reprinted in 100 Wild Little Weird Tales, edited by Robert Weinberg, Stefan R. Dziemianowicz and Martin H. Greenberg, Barnes and Noble, 1994.
- Underwood, Peter. (1985). Ghosts of Somerset. p. 41. St. Teath, Bodmin, Cornwall: Bossiney Books.
- England & Wales, National Probate Calendar (Index of Wills and Administrations), 1858–1966 for Elliott O'Donnell- Ancestry.com – pay to view
- Elliott O'Donnell at the Internet Speculative Fiction Database
- Works by Elliott O'Donnell at Project Gutenberg
- Works by or about Elliott O'Donnell at Internet Archive – including images of some books published as by Elliot O'Donnell
- Works by Elliott O'Donnell at LibriVox (public domain audiobooks)
- Elliott O'Donnell at Library of Congress Authorities, with 40 catalogue records