Quarterback Eli Manning and New York Giants brass created bogus “game-worn” football gear to pass off as the real deal — and one of the forgeries is sitting in the Pro Football Hall of Fame, an explosive new lawsuit claims.

A helmet on display in the hallowed Canton, Ohio, gridiron museum — supposedly worn by Manning in Big Blue’s 2008 Super Bowl victory over the New England Patriots — is just one of dozens of fake items the football superstar and his Giants cohorts have created to fool fans and make money from collectors over the years, the lawsuit alleges.

Other “forgeries” passed off on collectors include several Manning jerseys, two 2012 Super Bowl helmets and a 2004 “rookie season” helmet, according to court papers.

Two-time Super Bowl MVP Manning took part in the scheme so he could hang on to his personal items, according to the documents.

The memorabilia ruse is so common among Giants players and staffers, the documents claim, that team equipment manager Joe Skiba openly discussed Manning’s fake game gear on an official Giants e-mail account.

The lawsuit emerged as Manning’s big brother, Peyton, prepares to lead the Denver Broncos against the Seattle Seahawks in Sunday’s Super Bowl at MetLife Stadium, the Giants’ home field.

A rep for the Giants on Thursday said, “This suit is completely without any merit whatsoever and we will defend it vigorously. We will not otherwise comment on pending litigation.”

Peyton Manning had no comment when asked about the suit.

The allegations are part of a civil-racketeering, breach-of-contract, malicious-prosecution and trade-libel suit filed Wednesday in Bergen County Superior Court by sports collector Eric Inselberg.

In one startling claim, the suit says Barry Barone, who has been the Giants’ dry cleaner since 1982, used his Rutherford, NJ, Park Cleaners store to beat up jerseys and other items at the behest of longtime locker-room manager Ed Wagner Jr.

In a 2001 incident, Wagner told Barone “to intentionally damage multiple jerseys to make them appear to have been game-worn when they had not been.”

Inselberg’s lawyer, Brian Brook of Clinton Brook & Peed, said his client walked in to find Barone “using a big pair of scissors to cut up a set of Giants’ 2000 season’s game-issued white jerseys,’’ in order to then “’repair’ those damages” to make the shirts look used.

Inselberg was indicted in 2011 for memorabilia fraud for selling bogus used sport jerseys from teams.

But federal prosecutors in Rockford, Ill., dropped all the charges in May 2013, telling the judge that “prosecution was no longer appropriate in light of some new facts that were pointed out to us by defense counsel.”

The case was jettisoned two days after Inselberg’s defense lawyers told the court that Giants staffers had lied to the grand jury that indicted him about their relationship with him, in a bid to cover up for the team’s own fake-memorabilia sales.

Wednesday’s lawsuit is Inselberg’s attempt at retribution against the Giants.

The new suit alleges that Wagner, along with Skiba and his brother, Ed, also an equipment manager, were told by team brass to lie to federal investigators and the grand jury about how much Giants sports gear they sold him over the years.

Among the many scathing claims that could tarnish Eli Manning’s squeaky-clean image is an alleged 2005 incident in which he allegedly asked Joe Skiba for an old, beat-up game helmet — and then took the headgear, signed it, and put it on the market, “falsely claiming that it was a helmet used during his 2004 rookie season.”

In 2008, the suit alleges, Joe Skiba took a different helmet and doctored it to appear as if Manning had worn it in that year’s Super Bowl. The fake headgear was ordered by a Giants vice president after he learned the real headgear had been sold — to Inselberg — and was later given to the Hall of Fame, the suit claims.

Two bogus helmets that Manning claimed to have worn in the 2012 Super Bowl, as well as jerseys and helmets from 2008, were also ordered to be doctored and then sold, according to the suit.

Included in the lawsuit is a 2008 e-mail exchange between Inselberg and Joe Skiba, in which Skiba appears to acknowledge he created fake game-worn gear at Manning’s request.

“Hey Joe, my buddy was offered an eli game used helmet and jersey. Are these the bs ones eli asked you to make up because he didnt want to give up the real stuff?” Inselberg writes in the exchange.

Skiba — replying from account “jskiba@giants.nfl.net” — writes, “BS ones, you are correct…”

Some of Manning’s alleged fakes were sold through famed memorabilia house Steiner Sports, with whom he had an exclusive deal.

Steiner, believing its items to be authentic, sold them “to unwitting customers and sent them via the mail,” the suit says.

Angry buyers started to complain after noticing that markings on their items didn’t match those that appeared in pictures of Manning’s game-day duds.

But Manning told Steiner they were legit, and Steiner resold returned helmets to other buyers, the suit claims.

Inselberg did not put a dollar amount on compensatory or punitive damages. But he lost “well into the eight figures,” according to lawyer Brook, who filed the suit with Red Bank, NJ, lawyer Michael Kasanoff.

Inselberg bought and sold legit game-worn memorabilia from several teams and had a lucrative business, the suit claims.

The Giants were his “largest supplier by far, via their equipment management staff [and] several players.”

Inselberg said he bought thousands of collectors items over the course of two decades directly from Giants staffers, including Wagner and the Skibas.

He also had separate business partnerships with the Skibas.

Inselberg says he knew the Giants and Manning were churning out fake, but believed he was getting legit products because of his close relationship with the team.

He was so close to the Giants leading up to his indictment that the team relied almost exclusively on Inselberg’s memorabilia to launch its Legacy Club, a historical showcase for the Giants at MetLife Stadium.

The lawsuit says that many of the game-worn items now showcased at the Legacy Club are items he got from Wagner and the Skibas.

When the club opened in September 2010, Giants CEO John Mara sent Inselberg a letter thanking him for lending his “extensive collection” to the team, and he was named “Giants Memorabilia Curator,” the suit says.

Inselberg claimed to have learned that the staffers, Manning and Giants management were churning out fake memorabilia after seeing it first hand, and discussing it with the Skibas.

According to the lawsuit, Joe Skiba told Inselberg that he “created fraudulent memorabilia at the direction of the Giants’ management and players,” including Manning.

For years, the Giants operated a racket in which they “repeatedly engaged in the distribution of fraudulent Giants memorabilia,” Inselberg claims.

They then “coerced and intimidated” Wagner and the Skibas “into lying to the FBI about it,” the suit alleges.

“When the Government came knocking on the Giants’ door, the response was a coverup that threw Inselberg under the bus to protect themselves and the team,” according to court papers.

The suit names Manning, the Giants, Inc., CEO John Mara, team lawyer William Heller, CFO Christine Procops, Wagner, the Skiba brothers and dry cleaner Barone as defendants.