A Saudi prince is the new owner of Joan Rivers’ Upper East Side penthouse triplex — but his plans for major renovations may earn the wrath of “Mrs. Spencer,” the lavish pad’s resident ghost.

Prince Muhammad bin Fahd, 65, bought the 5,100-square-foot spread at 1 E. 62nd St. for the asking price of $28 million.

The prince, however, is not impressed by the palatial home’s Versailles-inspired appointments, which include crystal chandeliers, five fireplaces, gilded walls and a sweeping staircase where Rivers loved to make dramatic entrances to thrill her guests.

Bin Fahd immediately brought in an architect and designers, sources told The Post.

“They were here a week after Ramadan,” which ended July 17, to start work on a gut renovation, one source said.

That’s where the prince might have a run-in with Rivers’ former nemesis, the late Mrs. Spencer, who was J.P. Morgan’s niece and the original resident.

In a 2009 episode of the TV show “Celebrity Ghost Stories,” Rivers said the pesky spirit was less than welcoming when she moved in 25 years ago and started renovating.

“It was just very strange,” Rivers said on the show. “The apartment was cold. I could never get any of my electrical things to work correctly.”

Even Rivers’ dog was spooked.

“I guess Mrs. Spencer is back,” the doorman told Rivers.

“I was absolutely desperate,” Rivers recounted to Varietyportal.com.

“Spencer was very angry,” Rivers said she eventually realized. “She was still, in her mind, the grande dame of the building. She did not like what was being done with the house.”

Rivers brought in a voodoo priestess, who performed a ceremony involving chanting and drumming.

The ghost was finally appeased when the comedienne hung a portrait of Mrs. Spencer in the building lobby and left flowers for her in the home’s ballroom.

Rivers’ former neighbors are also on edge, worried about not only the disruption of construction, but the prospect of big entourages and gun-toting bodyguards.

Though he’s a prince — son of the late King Fahd — bin Fahd will likely need the building’s permission to bring contractors in.

Rivers — who was born in New York and returned from the West Coast after her husband’s suicide — died at age 81 after a supposedly routine endoscopy last September.