ANAHEIM, Calif. — They stroll through Disneyland in packs of 20 or more, motley crews that resemble a cross between the Hells Angels motorcycle gang and a grown-up Mickey Mouse Club with their Disney-themed tattoos and their matching denim vests strewn with trading pins and logos.

Disneyland social clubs, by most accounts, are harmless alliances of friends and family who meet up at the park to share a nerdy obsession for all things Disney. With club names such as Tigger Army and Neverland Mermaids, how threatening can they be?

“It’s all about the shared love for Disney,” said Mark Drop Jr., 39, who founded a club called Flynn’s Riders, after a character in the Walt Disney animated film “Tangled.”

But a civil lawsuit filed in Orange County Superior Court has revealed a dark undercurrent to the pastime. The head of one club has accused another of using gangsterlike tactics to try to collect “protection” money for a charity fundraiser at the park.

The lawsuit reads like mob movie set in a theme park. The plot revolves around the Main Street Fire Station 55 Social Club, whose leaders claim they have been bullied and terrorized by the head of the White Rabbits Social Club.

The lawsuit names 19 members of the White Rabbits, accusing them of defamation, invasion of privacy, conspiracy and intentional infliction of emotional distress. It asks the court to reward the victims compensatory and punitive damages, to be determined during the trial.

The suit also names Disneyland, saying the park has failed to take action against the offending club. A park spokeswoman said Disney has not been served with the lawsuit and declined to comment further.

Some longtime Disneyland fans who are not involved with the clubs say the idea of adults forming clubs to show their love for the park is a bit strange but not dangerous.

“I’m not sure what Walt would think of big groups in matching biker vests walking down Main Street, but it’s not the most outrageous thing I’ve seen,” said Matthew Gottula, a 28-year-old marketing worker from Altadena who visits the park frequently.

Social clubs began forming at the Anaheim parks in earnest in 2013, according to longtime club members, who say they can’t remember who or what triggered the trend.

The park hosts about 100 clubs, ranging from five or six members to more than 100. Most members are adults, who own annual passes and meet at the park at least once a month.

The clubs’ common traits are their denim vests, adorned on the back with the Disney character that the club is named for and Disney trading pins on the front.

The vests are made to resemble those worn by motorcycle gangs. The Hells Angels and Mongols add the initials “MC” on their vests, for motorcycle club. The Disneyland clubs add “SC” on the vests, for social club.

“We just go to the park and socialize and ride the rides but we wear vests,” said Bill Oliver, 49, a service technician from Downey who started the Nightmare Crew social club three years ago. The club members are fans of Tim Burton’s movie “The Nightmare Before Christmas.”

Each club has its own rules for accepting new members. Some take a vote on new members while others have a probation period, during which the prospective member can wear a vest but cannot wear the club’s patch. That’s another tradition of motorcycle gangs.

Drop, the founder of Flynn’s Riders, said he has drafted a constitution for his club. It spells out that a prospective member must go through a three-month evaluation period before the club’s council members vote on admission.

A favorite club activity is called a “ride takeover,” in which members try to fill every vehicle of an attraction, said Roxy Tart, who founded the Bangerang Babes in 2014, a club of Tinkerbell fans whose members adorn themselves with glitter and sequins during park visits.

On a recent Sunday afternoon, several members of the Jack O’ Lanterns Social Club took over a vehicle on the Golden Zephyr swing ride at Disney California Adventure. As the silver spaceship vehicles swung around in a lazy circle, the Jack O’Lanterns waved their hands in the air like gleeful kids.

Club members count it as a small victory if they get enough members to fill every boat in the Pirates of the Caribbean ride at Disneyland or all the seats in Soarin’ Around the World at California Adventure Park.

“It’s as if you had fans of the same band or of the (NFL) Raiders,” Tart said. “It’s just a big group of people with something in common that they love.”

Club members acknowledge that they may look intimidating to other park guests as they walk in packs through the parks, dressed in ganglike regalia.

Drop, who wears a goatee and dark sunglasses, concedes that he might resemble a “gangster cholo guy.” But members say they try to be friendly in the park and explain to other guests that they have nothing to fear.

“We are grown-ups but we act like children in the parks,” said Oliver of the Nightmare Crew.

Members say the clubs don’t feud with each other. When one club crosses paths with another in the park, they usually stop to chat or exchange trading pins.

“Mostly when we see another club, we just wave,” said Michelle Mallek, 27, a teacher from Los Angeles and member of the White Rabbits Social Club, named for the rabbit most recently seen in the 2010 Tim Burton movie “Alice in Wonderland.”

Outside the parks, the clubs unite for barbecues or birthday parties at their private homes. Some members get together to organize fundraisers for homeless shelters or children’s hospitals.

That is where the problems arose between the Main Street Fire Station 55 Social Club, named for the fire station at Disneyland, and the White Rabbits, one of the largest clubs in the park.

John and Leslee Sarno, the founders of the Main Street Fire Station 55 club, claim in the lawsuit that they planned a memorial walk and fundraiser for Sept. 11, 2016, at Disneyland to benefit the families of the firefighters killed during the 9/11 terrorist attacks.

A week before the event, the lawsuit claims that John Sarno was approached by Jakob Fite, the head of the White Rabbits Social Club. Fite was backed by four of his fellow club members and the men demanded $500 to “protect” the event participants, the suit claimed. If Sarno did not pay, Fite and his White Rabbits would make sure Sarno would never get into the park again, the lawsuit said.

Sarno refused to pay and claimed in the lawsuit that Fite and his allies have since spread malicious rumors about him on social media sites visited by Disneyland social clubs and on a podcast hosted by Fite.

The suit also contends that Fite distributed Sarno’s medical information to “unauthorized users,” in violation of federal privacy laws. The lawsuit names Kaiser Foundation Health Plan as a defendant, claiming the medical insurance company failed to protect Sarno’s medical information.

Kaiser issued a statement, saying: “We’re aware of the lawsuit and can’t comment due to the pending litigation.”

Fite, 42, a sound engineer from Apple Valley, rejected the allegations in the lawsuit, saying Sarno filed the suit to fire back at Fite for raising questions about Sarno’s character among other Disneyland social clubs.

Fite cohosts a podcast that discusses Disney’s subculture and said he used that forum to raise questions about Sarno’s character and suggest that Sarno has been misleading club members about his background to raise money for charitable causes.

Through their attorney, John and Leslee Sarno declined to comment on the lawsuit.

In an email, the Sarnos’ attorney, Patricia Kramer, said the couple “have no desire to further publicize their circumstances or to take any action that could be construed as their own re-publication of the false and defamatory statements that have been circulated by the defendants in this case.”

Other social club members say the dispute between Sarno and Fite does not reflect the behavior and attitude of most clubs at the park. Individual members may not get along, they say, but the clubs don’t go to war in the park like in the musical “West Side Story.”

Jesse Flores, a 35-year-old truck driver from Los Angeles, who formed the Sons of Anakin Social Club four years ago, said he is aware of the dispute between Fite and the Sarnos. The club was named for a Star Wars character.

“It’s happening on a personal basis,” he said of the dispute. “It’s not a club thing.”

Jessica Fowler, a 26-year-old medical biller from Dana Point, said she joined the White Rabbits last year because she was looking for friends who would share her love of the park. The club has become like a family, she said, adding that she would never start a beef with another club in the park because she worries that Disney officials will revoke her annual pass.

“This is a big part of me,” she said.