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This Halloween, you have a ghost of a chance of seeing a celebrity.

Let me rephrase that. This Halloween, you have the chance to see a celebrity ghost.

Where do these apparitions hang out? Well, mainly, they spook the two cities that living stars are partial to: New York and Los Angeles.

Storied landmarks with reports of rich-and-famous hauntings in the Big Apple include the Algonquin Hotel (search), home to the spirits of Dorothy Parker (search), Harpo Marx (search) and other members of the well-known literary "Round Table"; the White Horse Tavern (search), where poet Dylan Thomas (search), a former regular patron, is believed to still be looming; the New Amsterdam Theatre (search), which houses the specter of Ziegfeld Follies girl Olive Thomas (search) (no relation to Dylan); and the restaurant One If By Land, Two If By Sea (search), one of whose many phantoms is said to be former Vice President Aaron Burr (search).

“When you have personalities of that kind of strength, they hang around,” Algonquin historian Barbara McGurn said of the spooks at her hotel. “None of them was a shrinking violet.”

There are also rumors that the ghosts of John Lennon (search), "Frankenstein" actor Boris Karloff (search) and other former tenants loom at the well-to-do Manhattan apartment building called The Dakota (search) (Lennon was shot to death outside the front door), though managers deny there have been any sightings or hauntings there.

In Los Angeles, Marilyn Monroe (search) and 1950s “From Here to Eternity” actor Montgomery Clift (search) have been spotted paying a visit to the Hollywood Roosevelt Hotel (search), where both stayed as guests; 1920s “Phantom of the Opera” actor Lon Chaney (search) has been seen scurrying along catwalks in a black cape at Universal Studios (search); and 1920s movie star Rudolph Valentino (search) has a ghostly veiled woman who brings fresh flowers to his grave at Hollywood Forever Cemetery (search).

The ghoulish sites are listed in "Top Haunted Spots" roundups on the "where-to-find-it" Web site Citysearch (search) for Savannah, Boston and other cities, in addition to New York and L.A.

Most of the star-studded, real-life haunted houses are places celebrities and artists of various stripes have always been drawn to.

The Algonquin has been home and hotel to a steady string of actors, writers, artists and others among the literati and glitterati since it opened in 1902. Among its famous faces through the decades: writers William Faulkner and F. Scott Fitzgerald; actors Peter O'Toole, Humphrey Bogart, Douglas Fairbanks and Tallulah Bankhead; and playwright Noel Coward.

But perhaps its most famous frequenters were members of the Round Table, who met at the same table at the hotel for lunch every day to exchange sharp witticisms and sarcastic quips.

Current staffers believe they haven't gone very far away.

"I think the spirits of the Algonquin are among us," said hotel general manager Anthony Melchiorri. "I've felt them, but I haven't seen them."

The Algonquin ghosts fable is so entwined in the hotel's history that every New Year's Eve at the stroke of midnight, its entire kitchen staff makes a tradition of marching around the building banging pots and pans to try to rid the place of specters. But they're stubborn.

"The ghosts, it seems, persist," McGurn said.

The resident cat, a silky Blue Point Birman (search) named Matilda, is apparently well-acquainted with the other-worldly beings.

"The cat seems to know things the rest of us don't know," said McGurn. "She could be looking at people she sees whom we can't. I think she tries to make peace among the various ghosts of characters who stayed here and lived here and partied here."

A few blocks away, the New Amsterdam Theatre contends with its own ghost, that of Ziegfeld Follies performer Olive Thomas, who has been seen floating across the stage in a green velour bodysuit with fur cuffs and a beaded headdress as she smiles and blows a kiss.

Born Oliveretta Elaine Duffy in 1894, she won the "Most Beautiful Girl in New York City" contest, which led to her Follies and film careers, her most famous movie being "The Flapper" (search).

But the rising star's life ended abruptly, under mysterious circumstances, while the almost 26-year-old was on vacation with her husband, actor Jack Pickford.

Her death was later ruled an accident, apparently caused when she mistakenly ingested mercury bichloride pills rather than her intended sleeping medicine — though some say she committed suicide and others believe she was murdered by Pickford.

A night guard saw her in 1997, the story goes, when the New Amsterdam Theatre's renovations were completed just before "The Lion King" opened there.

"We had a very frantic call from a security guard in the middle of the night," said Dana Amendola, vice president of operations for Disney Theatrical Group, who has been on the receiving end of some of the phoned-in ghost sightings. "While he was making rounds, he was onstage with a flashlight, and he felt a presence onstage with him.

"He saw a woman walk from one side of the stage to the other side of the stage. He said, 'Can I help you?' The woman blew him a kiss and walked through the wall."

After that, the man refused to do night shifts anymore, and the theater instituted a policy of scheduling guards in pairs, Amendola said.

Upon further research, the staff came across a book with a photograph of Thomas, wearing the outfit the man had described.

"This security guard had no theater experience, was not a costume designer and had never seen the picture," he said. "We found out there were several observations of her from those who worked in the theater, and they all say the same thing. ...

"People figure she's back in this place because this is where she spent her childhood. These were the happiest days of her life."

At the White Horse Tavern in Greenwich Village, the ghost of writer and poet Dylan Thomas — a twice-daily regular at the 1800s-era bar — is thought to cause a racket there from time to time.

Current bar manager Fran DeMastri said a porter who worked at the pub in the 1960s refused to close up alone after a few nights when he heard commotion while he was in the basement. He'd run upstairs to find the chairs he'd stacked were back on the floor and two glasses had somehow appeared on the table.

The bar hired another employee to work late nights with him. Both quit when the ghastly incidents kept happening.

"When you're in here by yourself, you swear something is happening in here," DeMastri said.

Not all the ghosts around town are famous. Former Vice President Burr — who killed Alexander Hamilton (search) in a duel — is rumored to haunt One If By Land, Two If By Sea in New York, but so are other unknowns.

At the carriage-house-turned-restaurant, a female ghost in a flowing white dress has been seen walking around, an African-American man asks to be seated, then vanishes, invisible shoes trudge on the steps, lights dim and the temperature plunges without explanation.

But employees say they're not sure who is lurking in the eatery. They just know someone is, and they think he or she has company.

"We don't know who could be haunting this place," said General Manager Rosanne Manetta. "I hate to say 'haunting' because I don't want to piss them off."

At Chumley's (search), an old Prohibition-era bar in New York City, employees believe that the former owner, Henrietta Chumley, is still on the premises — more specifically in the jukebox. Whenever they try to update its music, it doesn't work. And songs randomly begin playing, often appropriate to the situation at hand.

"After she passed away, there were numerous attempts to jazz it up," said manager Gina Ruiz. "She has never been scary or mean, but she's very adamant about not wanting new things."

When this reporter was there, asking questions about whether the ghost is friendly or scary, "I Want to Be Happy" by Doris Day came on, seemingly spontaneously.

"I'm sure she's playing that for you," Ruiz said, laughing.

Instead of getting frightened or frazzled about the lingering phantoms, most staff at the spooky sites welcome their apparitions with open arms.

“They’re wonderful ghosts,” McGurn said.

But in spite of her research, New York Citysearch editor Erin Behan, who compiled this year's 'Haunted Spots' list, never saw any of the specters herself. She doesn't think she ever will.

"I don't believe in ghosts," she said.