There's a long tradition of occult detectives in popular fiction dating back to Sheridan Le Fanu's Martin Hesselius, Bram Stoker's Abraham Van Helsing and William Hope Hodgson's Thomas Carnacki.

Comics, too, have an established history of the examiners of the unknown, from Doctor Occult to John Constantine to the denizens of the Hellboy universe (the Bureau for Paranormal Research and Defense, Lobster Johnson, Sir Edward Grey, et al).

For this list highlighting some of the medium's greats, I wanted to avoid the more popular, or more obvious, choices, such as Doctor Strange, Doctor Thirteen, Batman or the aforementioned Hellboy and Constantine. Most of them get plenty of ink as it is.

With that out of the way, here are six great paranormal investigators from comics (in no particular order, of course):

Dylan Dog

See that debonair fellow with the chiseled, Rupert Everett-esque features (Everett before that unfortunate facelift, in any case)? That's Dylan Dog, the forever-penniless "nightmare investigator" with a laundry list of neuroses -- acrophobia, claustrophobia and chiroptophobia, among them -- a fondness for the clarinet, a hefty Oedipus complex, and a father who may be the Devil. He's also the star of the bestselling Italian comic-book series. Created in 1986 by writer Tiziano Sclavi, Dylan is a former Scotland Yard detective who set out on his own after the death of his wife. Based out of his plush home at 7 Craven Road in London -- it's the house with the screaming doorbell, you can't miss it -- and aided by a sidekick who's either a Groucho Marx impersonator or the reincarnation of the comedian, Dylan waits for the next surreal case (and real paycheck) while he tinkers with a model ship that he never manages to complete.

The Kurosagi Corpse Delivery Service

The next time you grumble about your job, realize that it could be much, much worse. Take, for instance, the members of the Kurosagi Corpse Delivery Service (stars of the series of the same name by Eiji Otsuka and Housui Yamazaki). They're students at a Buddhist university who specialize in helping the spirits of the dead -- often those who have been gruesomely murdered -- to move on to their next incarnation. More often than not, that involves discovering the killer and then stepping aside while the restless spirit exacts its revenge. Luckily, the couriers are uniquely equipped for their occupations: There's the dowser who can locate the corpses, the psychic who can communicate with the dead, the computer expert, the licensed embalmer, and the medium who can channel a foul-mouthed alien intelligence via a hand puppet. Yeah, you read that last part right.

Agnes Quill

Like the Kurosagi crew, Dave Roman's plucky teenage detective makes a living by helping the departed resolve unfinished business so they can move on to the afterlife. Agnes also can see, and communicate with, ghosts, beginning with that of her grandfather, the famous detective Ages Quill. Based in a curiosity shop on the first floor of her inherited castle, Agnes prowls the streets, and catacombs, of Legerdemain -- it's a sprawling Victorian city built around an enormous cemetery -- tracking down criminals, dodging bullets, battling possessed teddy bears, and only occasionally getting paid.

Reiji Akiba

Private detective Reiji Akiba, the star of Housui Yamazaki's series Mail, likes to take a direct approach to dispatching spirits. None of that touchy-feely "What's troubling you?" stuff. Akiba comes armed with Kagutsuchi, a sanctified gun that fires bullets that send the sinister specters to ... well, wherever they're supposed to go. Heaven, hell, the otherworld. He also enjoys a good incantation. For example: "Dead soul, tearing at the living half. With my gun I admonish you. I trace you and I track you. From egg ... to womb ... to grave." Poetry, that.

Courtney Crumrin

The odd little girl with the bat barrette isn't an investigator in the strictest sense of the word. No, she's just nosy. And stubborn. And probably too smart for her own good. Unfortunately, when you're the niece of a powerful and feared warlock and live in a neighborhood populated by witches, goblins and talking cats, those personality traits can lead to no end of trouble -- and mysteries. Ted Naifeh's headstrong heroine pursues a kidnapped infant into the subterranean Goblin Town, exposes a conspiracy within the Coven of Mystics, discovers the ghostly secret of her friend's mother, and even tries to help star-crossed (and full-moonstruck) lovers.

Vol de Galle, The Marquis

On a list populated by characters who fight tooth and nail with the undead, handle mutilated corpses and even steal the decapitated head of a grotesque goblin (oh, Miss Crumrin!), Vol de Galle is easily the most troubling, disturbing and, perhaps, even disturbed entry. The protagonist of Guy Davis' action-horror series The Marquis, de Galle is a former Catholic Inquisitor in Venisalle, a fictional snow-covered land resembling 18th-century France, where the Church and a rigid class structure cast long shadows over everyday life. Seemingly blessed by the saints, de Galle possesses the ability to detect the demons who, disguised as humans, have escaped Hell to prey on his countrymen. Donning a black mask and costume, and wielding a sword and a pair of machine gun-style pistols, de Galle becomes The Marquis, the dark protector of Venisalle and destroyer of demons. That, or he's a madman suffering from delusions and hallucinations who has murdered countless (mostly) innocent people. Take your pick.