Of all the jaw-dropping things — movie-star affairs, secret parties and tragedies of many stripes — that have happened at the Chateau Marmont hotel in West Hollywood, the most notorious remains comedian John Belushi’s 1982 drug death.

Lesser known, however, are the stories of celebrity copycats who seemingly wanted to follow in his footsteps.

The “Saturday Night Live” star had been staying in one of the fabled bungalows, on a five-day cocaine and heroin bender. After getting so desperate that he reportedly called up his agent for drug money, Belushi invited over dealer/celebrity hanger-on Cathy “Silverbag” Smith (so named because she carried her contraband in a silver-colored bag).

According to the National Enquirer, Smith later said she actually shot up Belushi with the speedball that killed him: “his coup de grace … He had a death wish.” Just six years earlier, “New owners bought it with an eye to tearing [the hotel] down,” said Shawn Levy, author of “The Castle on Sunset: Life, Death, Love, Art, and Scandal at Hollywood’s Chateau Marmont” (Doubleday), out Tuesday. “But after Belushi died, the place was on the map.”

In fact, his tragic demise inspired fellow famous druggies — including artist Jean Michel Basquiat — to ask to stay in the Belushi bungalow. Funk musician Rick James did so and, Levy told The Post, overdosed himself. “He had to be revived while staying at the hotel,” Levy said.

As 1930s studio boss Harry Cohn — who kept a suite at the hotel for extramarital antics with starlets — once told his Columbia Pictures actors: “If you must get into trouble, do it at the Marmont.”

‘If you must get into trouble, do it at the Marmont.’

Plenty of boldface names found trouble there. Doors frontman Jim Morrison once jumped off a balcony, and was known to leave bloody sheets in his bedroom for the maids to clean up. James Taylor shot heroin in front of Carly Simon in his room. Members of Led Zeppelin raced through the halls on bellhop trollies, and Marvin Gaye died owing the hotel $15,000.

And then there was vintage star Jean Harlow. In 1933, the actress was staying at the Chateau Marmont with her brand new hubby No. 3, Harold Rosson. The newlyweds stayed in a room adjoining the one where Harlow was also having an affair with Clark Gable.

Built in 1929, the Chateau was modeled on an actual castle in France’s Loire Valley, the Chateau D’Amboise, a onetime home of Mary, Queen of Scots.

It was originally an apartment building but, by the 1950s, had evolved into a hotel that functioned as what Levy called “an open city. It was Casablanca.”

People secretly had affairs, took drugs and licked wounds from botched relationships. They also broke societal barriers.

“It was the first show-biz hotel to allow black people,” Levy said. “And gay Hollywood hung out at the pool. [Fifties heartthrob] Tab Hunter — stopping by for a dip on his way home from horseback riding in the Valley — met Anthony Perkins there, and they began a two-year affair. Gore Vidal called the pool ‘a navel filled with sweat.’ ”

Director Nicholas Ray retreated to the Chateau Marmont after walking in on his wife, actress Gloria Grahame, having sex with his son from a previous marriage.

But Ray — who was also spotted slow-dancing in his bungalow with another man — found plenty of comfort at his new home.

Levy described Ray as “being out of his skull” and throwing regular Sunday afternoon pool parties that attracted a mix of studio executives and kids from nearby Hollywood High.

Among the kids hanging out with the director in his bungalow was 16-year-old Natalie Wood, one of the stars of his 1955 film “Rebel Without a Cause.”

Despite a 27-year age difference, the two were having a torrid affair — even as Wood was also sleeping with her co-star Dennis Hopper. (Reportedly, Hopper would go on to host orgies at the Chateau.)

“Nick and Dennis were both having sex with Natalie,” said Levy, adding that Ray sated his jealousy by cutting Hopper’s screen time. “Ultimately, Natalie chose to be with Ray.”

The past two decades have also seen plenty of insanity — and tragedy.

In 2004, fashion photographer Helmut Newton died after losing control of his car while pulling out of the Chateau’s driveway.

That same year, rumors flew that actors Benicio del Toro and Scarlett Johansson had hooked up in a hotel elevator after the Oscars. More recently, stars have been kicked out of the Chateau for their bad behavior.

After winning at the Screen Actors Guild awards in 2006, Heath Ledger was surreptitiously filmed using cocaine on the hotel’s front balcony. (The actor died of an overdose two years later.)

Britney Spears reportedly was banned in 2007 for boorish table manners, while Lindsay Lohan was booted in 2012 after not paying her $46,000 tab.

And there’s no shortage of lush life at the hotel, where a penthouse rents for $5,000 a night.

In February, Jay-Z and Beyoncé threw an Oscars bash in the Chateau’s garage redone to resemble a luxe lounge. Revelers such as Jamie Foxx, Rihanna and Leonardo DiCaprio feasted on caviar and swigged Ace of Spades champagne.

The hotel has been immortalized in songs (including Lana Del Rey’s “Off to the Races”), film (“La La Land” and Sofia Coppola’s “Somewhere”) and books (“The Big Nowhere” by James Ellroy).

But even the most outrageous fictions could not live up to the reality of what’s gone down there, including Billy Idol trashing his room before standing buck-naked on his balcony. As Levy said, the Chateau Marmont “was the hotel where you could do what you wanted.”