Leonard Nimoy’s son remains tight-lipped on why his late dad was feuding with William Shatner: ‘I know why’

Adam Nimoy knows why his late father, Leonard Nimoy, stopped speaking to his “Star Trek” co-star William Shatner in the last five years of his life — but isn’t about to spill the tea.

“I know why,” Adam, author of “The Most Human: Reconciling with My Father, Leonard Nimoy,” teases in an exclusive interview with Page Six, before adding that he intends to “let sleeping dogs lie.”

“It’s unfortunate, it’s sad,” he continues, calling the pair’s relationship, “very challenging” despite “a period of time where they were really beautifully together.”

Leonard Nimoy’s son, Adam Nimoy told Page Six he knows why his dad, Leonard Nimoy, stopped talking to William Shatner. WireImage Adam remained tight-lipped on the reasoning for their feud at the end of his father’s life. Getty Images

Adam explains that he and his sister Julie would hear stories of his dad sparring with Shatner on the “Star Trek” set, so they were surprised when Leonard referred to the actor as his “best friend” in a memoir.

“Julie and I were scratching our heads like … you’ve knocked heads with Bill, all your professional life,” he explained.

“And now they had some reconciliation and it was beautiful, but it just didn’t. They just couldn’t sustain it. And that’s unfortunate.”

Leonard and Shatner worked together on the “Star Trek” television series and movie franchise. Getty Images “It’s unfortunate, it’s sad,” Adam said of their beef. Getty Images

Shatner, 93, expressed grief when Nimoy died in 2015 at age 83.

“I loved Leonard as my dearest brother,” he shared. “When he died, a part of me died.”

However, Shatner skipped his supposed best friend’s funeral, saying he felt “really awful” about it but had a prior charity commitment to fulfill instead.

Shatner and Leonard reconciled at one point, but couldn’t “sustain it,” according to Adam. Getty Images Shatner recounted his friendship with Leonard in a memoir. Getty Images

In 2016, the “T.J. Hooker” alum penned a memoir, “Leonard: My Fifty-Year Friendship with a Remarkable Man,” in which he revealed that he and Nimoy were not on speaking terms for the last five years of Nimoy’s life.

In the book, Shatner chalked it up to trying to include Nimoy in a “Star Trek”-related documentary without his permission.

In an interview with The Hollywood Reporter, Shatner referenced the doc but ultimately claimed he didn’t know the reasons behind the rift.

He acknowledged that they weren’t speaking when Leonard died. Getty Images George Takei, who played Sulu, also had a strained relationship with Shatner. CBS via Getty Images

“I don’t know why he stopped talking to me,” he said, calling the turn of events “sad” and “permanent.”

Nimoy wasn’t the only “Star Trek” actor who feuded with Shatner.

George Takei, who played Hikaru Sulu, has badmouthed Shatner for over forty years and has accused Shatner of ignoring him on set and even tinkering with the script for “Star Trek V” so Sulu would not receive command of a spaceship.