ABOUT SIX MONTHS into the Broadway run of "Dracula," its star, Frank Langella, was in a costumer's on 19th Street being fitted for a new cape.

From the next booth, Langella overheard a smooth Gallic voice murmuring, "I think perhaps the points should stand away like this." Langella climbed onto the chair, looked over the partition at Louis Jourdan and smiled. "Good evening, Count Dracula," Jourdan, without missing a beat, bowed: "Good evening, Count Dracula."

For a man in his 50s, Dracula seems to be in the absolute prime of life, this summer alone swirling through three movies and casting a shadow over a couple more; in his third reincarnation at the Martin Beck Theatre (now starring French-Canadian Jean LeClerc) and going strong off-Broadway at the Cherry Lane.Dracula has materialized in two different television specials in the last three years, three series in the last decade (four if you count the spoofy "Adams Family") and has another pilot in the works.

The pilor for "The Night Stalker" became at the time of its airing the highest-rated made-for-TV movie ever shown. There have beee vampire themes invented for series as wide-ranging as "McCloud" and "The Hardy Boys." Barnabas Collins, the family vampire, became by far the most popular character on the soap opera "Dark Shadows." Pular character on the soap opera "Dark Shadows." There have been more than 200 feature films strarring Dracula, beginning with the great German silent film "Nosferatu" in 1922 and leading up to the lush new "Dracula" being released on Friday. In between, the Count has had daughters, brides, encounters with Frankenstein and the Wolfman; been black, been gay and baffled by Manhattan.

He and his ilk have starred in uncounted stories, ballads, poems and novels since before recorded history. Shelley wrote about them, and de Maupassant, Goethe, Dryden, and Scott. The Anglo-Saxon passion for vampires was born with the 1846 penny-dreadful, "Varney the Vampire" and bloomed 50 years later with the publication of Bram Stoker's Dracula." Stoker's novel is still so popular that it is currently available in a dozen different editions, and Jove Paperbacks has just issued 300,000 new copies (in the 13th edition) with Langella's picture on the cover and movie stills inside.

Dracula's enduring fascination, Langella believes, is simply a matter of the strong human interest in "sex and immortality." Leonard Wolf, editor of "The Annotated Dracula," also seems the attraction of Dracula's aristocratic sophistication.

"What an elegant monster he is!" writes Wolf. "How strong, how graceful, how lonely, how wise. And above all - and here is his central mystery - how deadly . . . and how erotic." Stoker reflected the confused and contorted Victorian emotions about women in "Dracula, the perfectly discreet lover. According to Stoker's grand-nephew and biographee, Stoker's wife stopped having a sexual relations with him after the birth of their son in 1879. Stoker became something of a ladies' man in London and Paris, where he traveled as actor Sir Henry Irving's manager, and eventually died of tertiary syphilis.

Certainly in the past several years, Dracula has been portrayed by attractive men: Jourdan, Langella, Raul Julia, George Hamilton, Michael Nouri from the "Cliffhangers" TV series, and former soap opera idol David Combs from the off-Broadway "Passion of Dracula."

And the advertisement for various "Draculas" have become increasingly romantic. The new film is billed as "A Love Story"; poster ads during Julia's tenure hinted, "Nobody does it better." A previously unpublished chapter from Anne Rice's "Interview With the Vampire," recording the Count's musings on love and sex, was printed in Playboy magazine.

In recent years, too, several notorious mass-murder and "vampire killers" cases have been splashed across the tabloids, to the point where Dracula seems an unusually suave character.

In the spring of 1973, following the success of a book called "In Search of Dracula" by Radu Florescu and Raymond McNally, New York's General Tours packaged a "Tour of Dracula Country": round-trip fare on Pan Am from New York to Romania and guided tours through the castle ruins for only $935.

Even outside the "Dracula mold, vampires mean big bucks. Another Tony-winning Braodway production, "Sweeney Todd, the Demon Barbeer of Fleet Street," is a vampire story, and based on a penny dreadful by the author of "Varney the Vampire." The title character of "Alien" is the ultimate outer-space vampire; the stars of "Nightwing" are vampire bats controlled by an Indian shaman.

Satire is nearly as profitable. Roman Polanski led the way with his slapstick "The Fearless Vampire Killers." Hamilton's loopy "Love at First Bite," which has revived his undead career, is headed toward a sequel (tentatively titled "Divorce, Vampire Style"). President Carter screened "Bite" at the White House; the deposed shah of Iran had it flown in to his Bermuda hideaway. Home Box Office offers a National Lampoon cable-TV movie called "Disco Beaver from Outer Space," which features a gay vampire named "Dragula." A new kung-fu movie playing about town these days announces, "The 7 Brothers Meet Dracula," first to fang.

Dracula has been transformed into a breakfast cereal (Count Chocula) and exploited as a spokesman for high-blood-pressure testing. Langella was invited (but refused) to turn Dracula into a TV series hero: as a crime-fighting fly-by-night, complete with all-black jet.

Still to come on the movie screen are an English-dubbed version of "Nosferatu" by German director Werner Hertzog, starring Isabel Adjani; a movie version of "Interview With the Vampire," and a Romanian film that seeks to rehabilitate the reputation of the 15-century Wallachian prince, Vlad Dracula, on whom Stoker based his vampire.

MTM Productions, whose previously nonviolent TV series included "The Mary Tyler Moore Show" and "The Bob Newhart Show," is working up a pilot about a vampire who is "disrupted" by the construction of a new church and sets out to destroy the architect (Jason Miller of "The Exorcist") and his wife. After her murder, Miller heads out on a "Fugitive"-style never-ending chase.

It gets worse. Stern, a maker of pinball machines, is developing a "Dracula" model. New Wave guitarist Hugh Cornwell of the Stranglers will release a solo album this month called "Nosferatu." And John Carradine, along with Lugosi and Christopher Lee one of the most prolific screen Draculas ever, is lending his talents to a musical called "Nocturna," about the count's granddaughter falling in love with a rock musician.

At this point, even Dracula would probably be glad to rest in peace. CAPTION: Picture 1, no caption; Picture 2, Frank Langella, By Harry Naltchayan - The Washington Post