“I Love Lucy” star William Frawley was such a snob that he referred to his on-screen wife, Vivian Vance, as a “miserable c–t.”

Tim Considine, 81, revealed how Frawley harshly insulted Vance on the set of their 1960s comedy ‘My Three Sons’ during a visit from a lieutenant general and his adjutant in an interview with Page Six.

The officer was stopping over to say hello to Considine, who was in the Air Force Reserves at the time. Frawley, who also starred in the musical, joined the visitors for lunch.

The four of them began strolling back to the set after a delicious meal.

“I was thinking, ‘Hey, this is a great success. [Frawley] hasn’t said anything to put anyone off.’ I was pretty pleased with myself,”  Considine recalls.

During their way back to the studio lot, however, Considine’s relief swiftly changed to dismay when the lieutenant general asked Frawley what Vance was actually like.

He said, ‘I saw it coming.’

The first words out of Frawley’s lips in response were, “That miserable c–t.”

On the iconic 1950s comedy, which ran from 1951 to 1957, Frawley and Vance played Fred and Ethel Mertz, Lucy and Ricky Ricardo’s landlords and best friends. However, it was common knowledge that they detested each other.

In his book ‘I Love Lucy: The Untold Story,’ Gregg Oppenheimer, the son of ‘I Love Lucy’ producer and head writer Jess Oppenheimer, reported of their conflict.

Frawley and Vance had a good working relationship, according to his father’s perspective, until he overheard her make a critical remark about his age.

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‘Even though the entire world loved Lucy, everyone on I Love Lucy didn’t love everyone else,’ he wrote.

‘For one thing, Vivian Vance couldn’t stomach Bill Frawley. Actually, they got along quite well at first.

‘But before long, Viv became upset at the fact that people so readily accepted her lovely young self as the wife of “that old man,” as she called him.’

Audrey Kupferberg, who co-wrote “Meet the Mertzes: The Life Stories of I Love Lucy’s Other Couple” with her late husband, Rob Edelman, claims he was far worse than the public perceives him to be and that his portrayal in “Being the Ricardos” was sanitized. (For his depiction of Frawley, J.K. Simmons is nominated for an Academy Award for Best Supporting Actor.)

Kupferberg tells Page Six, “I was very upset over the movie. I thought J.K. Simmons, who’s a really good actor, his character was just not like Frawley was. They really warmed him up. The idea that he took a drink or two … he was really a very, very bad alcoholic.

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Frawley “drank all day” on set, according to the author. “And in between sets, he would move the party to a bar called Nickodell.”

“He drank all day. He would go across the street. He would go to a place called Nickodell,” adds. “He would drink there, and then after work, he would drink more. He was also really cheap, and when Nickodell raised the price of their beer by 10 cents a glass, he stopped going there and went to Musso and Frank.”

Frawley, according to Kupferberg, was “a mean, rough man.”

“He was a woman-hater, known throughout Hollywood for very bad language and just antisocial behavior.”