The book provides about 650 entries written by 65 contributors including Ramsey Campbell, Gary William Crawford, John Crowley, Thomas M. Disch, Ron Goulart, S. T. Joshi, T. E. D. Klein, Kim Newman, Darrell Schweitzer, Whitley Strieber, Timothy Sullivan, Colin Wilson, and Douglas E. Winter.

In order to provide as broad as possible a study of fear, terror, and horror throughout the centuries, the book features numerous entries on "mainstream" artists who Sullivan notes "have dabbled in or plunged into horror", such as Charles Baudelaire, Thomas Hardy, Henry James, Franz Kafka, Edith Wharton, Sergei Prokofiev, Charles Dickens, Heinrich von Kleist, Herman Melville, Joyce Carol Oates, Franz Liszt, Arnold Schoenberg, William Butler Yeats, and Isaac Bashevis Singer, among others.

Hundreds of genre author entries are provided, including "William Beckford" by E. F. Bleiler, "Ambrose Bierce" and "Algernon Blackwood" by Jack Sullivan, "Ramsey Campbell" by Robert Hadji, "Robert W. Chambers" by T. E. D. Klein, "James Herbert" by Ramsey Campbell, "Shirley Jackson" by Sullivan, "Stephen King" by Don Herron, "Arthur Machen" by Klein, "Ann Radcliffe" by Devendra P. Varma, and "Peter Straub" by Patricia Skarda.

Theme essays include "Arkham House" by T. E. D. Klein, "The Continental Tradition" by Helen Searing, "English Romantic Poets" by John Calhoun, "Golden Age of the Ghost Story" by Jack Sullivan, "Illustration" by Robert Weinberg, "Opera" by Arthur Paxton, "The Pits of Terror" by Ramsey Campbell, "The Pulps" by Ron Goulart, "Shakespeare's Ghosts" by John Crowley, "Urban and Pastoral Horror" by Douglas E. Winter, and "Zombies" by Hugh Lamb.

Film and television related entries include "The Abominable Dr. Phibes", "Tod Browning", "Brian De Palma", "Eraserhead", "Inferno", "Boris Karloff", "Night of the Living Dead", "Roman Polanski", "Suspiria", "Salò, or the 120 Days of Sodom", and "The Wolf Man".