Dylan Dog is a penniless nightmare investigator who defies the whole preceding horror tradition with a vein of surrealism and an anti-bourgeois rhetoric. The true monsters in many of these stories are human beings.
The series is mainly set in London, where the protagonist lives, though he occasionally travels elsewhere. His clothes are one of his defining characteristics: he always dresses the same way, in a red shirt, black jacket, and blue jeans. He bought twelve identical outfits after the death of his wife Lillie Connolly on the advice of Inspector Bloch, who was his superior when he worked at Scotland Yard and remains his father figure (in fact he calls Dylan "Old boy") even after Dylan struck out on his own to become a private investigator specializing in the supernatural. Inspector Bloch is one of the principal supporting characters in the series, together with his assistant (or rather, comic relief), Groucho, a punning double of Groucho Marx.
Dylan lives with Groucho at 7 Craven Road in a cluttered apartment with a doorbell that screams. His hobbies include playing the clarinet and constructing model ship; he has many phobias, including claustrophobia, bats and heights. Dylan is also particularly susceptible to motion sickness, which is one of the reasons why he rarely travels. Once an alcoholic, he now almost never drinks, though many of the most entertaining moments in the comic occur when Groucho forces him to take shots. He is a vegetarian. He's also a hopeless romantic who loves and loses a new woman in nearly every issue.
Dylan Dog seems to have an Oedipus complex: many of the numerous women he pursues resemble his mother Morgana, and he dramatically collides with the shadow of his father -- Xabaras -- (Slight transformation of Abraxas) cut into two halves, which seems to allude to the ambivalence of this father figure and of Dylan's feelings for him.
Sclavi's progressive disinvolvement has left other authors the task of carrying forward character continuity. After being absent for several years, Xabaras returned in 2004.
Groucho was a Groucho Marx impersonator whose character became his permanent personality (hinted to be because of memory loss in 'Oltre la porta' issue 228). Now he lives and works with Dylan Dog as his professional sidekick. He enjoys puns and women, though he does not share his employer's luck with the ladies. Groucho's goofy, off-beat personality helps temper Dylan's moodiness. He also reminds his boss when their finances are in dire straits (almost always), shows up with a pistol in the nick of time (he can't shoot himself, but he always throws the pistol in Dylan's hand right on time), and makes tea. At some point in every issue Groucho makes one or two jokes that annoy Dylan and the person listening to the joke (often a client of Dylan's). An example: "...once, I had a dog which could utter its own name. It was named Woof.
Dylan Dog series debuted in October 1986 with a comic book entitled "L'alba dei morti viventi" ("Dawn of the Living Dead"), plotted and scripted by Tiziano Sclavi and illustrated by Angelo Stano; it proved to be a huge publishing success in the years to come. May 2003 saw the publication of Issue 200, entitled "Il numero duecento" ("Number Two-Hundred"), plotted and scripted by Paola Barbato and drawn by Bruno Brindisi.
The first reprint series came out in July 1990, the second in June 1991, and the third in June 1996, this time called Collezione Book (Collection Book); in October 2006 the bi-monthly reprint Grande ristampa was released.
February 1997 saw the release of the Super Book, a tri-monthly release that reprinted the special annual issues that had come out ten years before.
In August 1987 a special annual release was added to the monthly series, called Numero Speciale (Special Issue), with one story longer than usual and, in addition, small extra books on various horror-related subjects.
Another annual release was added in March 1991, L'almanacco della paura (The Fear Almanac), together with the usual Dylan stories, one could also find articles and curiosities about film, literature, and other topics, all related to the horror theme.
January 1993 saw the appearance of a new annual book, the Dylan Dog Gigante (Gigantic Dylan Dog), so called because it was much larger than the monthly book and because it contained more stories.
Dylan Dog maxi (Maximum Dylan Dog) came out in July 1998. This was another annual release that collected together three previously unpublished stories.
In October 1990 an irregularly numbered issue came out: Dylan Dog e Martin Mystère - Ultima Fermata: l'incubo! (Dylan Dog and Martin Mystère - Last Stop: Nightmare!). It presented an unpublished story in which the nightmare investigator teamed up with another famous Bonelli character, Martin Mystère. Alfredo Castelli and Tiziano Sclavi wrote and plotted this story, and Giovanni Freghieri did the drawings. The story had a sequel in 1992.
American publisher Dark Horse Comics has released seven English volumes of Dylan Dog -- six in 1999, and one more in 2002. In this version, Groucho becomes a cleanshaven fellow called Felix because of legal dispute with Groucho Marx's estate. Mike Mignola drew new covers for the 1999 releases.
A new volume, Dylan Dog Casefiles, is planned for 2009, to tie in with the upcoming movie, Dead of Night.
Francesco Dellamorte also appears in a short sequel of Orrore nero, entitled Stelle cadenti (Falling stars), where Dylan, Groucho, Francesco and Gnaghi are walking together during saint Lawrence's night, watching shooting stars and talking bout life and death. But they are not alone, that night...
English actor Rupert Everett played the protagonist, Francesco Dellamorte, and Italian model and actress Anna Falchi played the female lead. Although Everett, playing Dellamorte, wore Dylan Dog's trademark costume, the Dylan Dog character did not appear in the movie.