For George Jacobs, whose business card proclaimed him “The Last of the Rat Pack,” there were some very good years.

From 1953 to 1968, he was Frank Sinatra’s valet, traveling companion and pal, a gentleman’s gentleman who poured the Jack Daniel’s at cocktail time and stayed all night to play poker.

At Sinatra’s California homes in Palm Springs and Bel-Air, Mr. Jacobs cooked the pasta, pressed the suits, found the girls. Sinatra cried on his shoulder about his lost love, Ava Gardner. Marilyn Monroe cried on his shoulder about Sinatra.

The product of a rough-and-tumble background, Mr. Jacobs got up close and personal with global figures. He had a spirited talk about women with John F. Kennedy while giving the future president a massage.

Sinatra’s mobster friend Sam Giancana joked about trying to hire him away. Mr. Jacobs later observed that Giancana, the late mafia boss accused by conspiracy theorists in the JFK assassination, “had the most perfectly manicured hands and nails I had ever seen.”

George Jacobs worked 15 years as Frank Sinatra’s valet and later wrote a memoir about his experiences. (Gina Ferazzi/Los Angeles Times)

“It was an amazing trip, and even more amazing that a poor black kid from Louisiana like me got to take it,” he wrote in “Mr. S: My Life With Frank Sinatra,” a tell-all 2003 memoir he co-wrote with William Stadiem.

Mr. Jacobs died Dec. 28 at a Palm Springs nursing home, said his son, artist Snake Jagger. He was 86. The cause was not disclosed.

Born in New Orleans on April 29, 1927, Mr. Jacobs spent days with his mother, a cook for a wealthy family in the city’s Garden District, and nights with his father, the owner of a honky-tonk called the Joy Tavern.

In 1945, Mr. Jacobs joined the Navy, trained as a ship’s cook and became an aide to an admiral. While on an aircraft carrier off Korea, he was told that his father had been fatally shot in a robbery. Back in New Orleans, he learned that his dad was killed by gangsters squeezing him for money with the aid of police.

Disgusted with his home town, Mr. Jacobs moved to Los Angeles and took a series of odd jobs — gardener, process server, an extra in “cheesy MGM ‘Tarzan’ knockoffs” — and wound up working Hollywood parties for a caterer. In 1950, he caught the eye of superagent Irving “Swifty” Lazar who hired him as a Man Friday.

When Sinatra hired Mr. Jacobs, three years later, the legendary singer and his new valet hit it off.

A prankster, Sinatra sent Mr. Jacobs to Tijuana, Mexico, to load up on cherry bombs that he’d explode in toilet bowls. “The Hoboken Bomber strikes again!” Sinatra would cackle.

“Today they’d give him Ritalin,” Jacobs wrote. “He couldn’t sit still and he couldn’t be alone.”

Sinatra had a famously insatiable sexual appetite, whether for well-known actresses or cocktail waitresses.

More than once, Mr. Jacobs wrote, he’d have to drive Sinatra’s conquests home in the middle of the night after his boss deemed their perfume excessive.

Just as Sinatra and the other members of his inner circle ribbed each other with derogatory ethnic names, he sometimes called Mr. Jacobs “Spook.”

“I took it as a brotherly nickname, not a racial epithet,” Mr. Jacobs wrote.

In 1960, Sinatra campaigned for Kennedy and, after his victory, prepared his Palm Springs home for presidential visits. He was devastated when family patriarch Joseph Kennedy ruled that Sinatra’s unsavory associations made his home off-limits for the president-to-be.

Mr. Jacobs said his boss was upset, “like a little kid and nearly in tears.”

It was Mr. Jacobs who was in tears a few years later. Sinatra was in the midst of a divorce from Mia Farrow, and Mr. Jacobs ran into her at a Los Angeles club. When gossip columnist Rona Barrett printed an item about the two dancing together, Sinatra was infuriated.

Returning to Sinatra’s place in Palm Springs, Mr. Jacobs found that the locks had been changed. A letter from Sinatra’s lawyer told him he was terminated.

“I had no idea it was a sin what I did,” Jacobs told the New York Times in 2003. “She was like one of my children. I’ve got shoes older than her.”

In his later years, Mr. Jacobs occasionally showed tourists through Sinatra’s former estate, which had been turned into a venue for weddings and corporate retreats.

For a few years, he tried his hand at carpentry. He worked for Steve McQueen and Bill Cosby. He also sang on “The Gong Show” and appeared on “The Dating Game.”

Mr. Jacobs was married and divorced three times, his son said. Survivors include six children. Three other children are no longer living.

Mr. Jacobs’s book was denounced as character assassination by Frank Sinatra Jr.

But for Mr. Jacobs, “it relieved a lot of my thoughts and tensions,” he told the Los Angeles Times. “I used to sit and cry a lot. I wasn’t keepin’ it goin’. So this really helped.”

—Los Angeles Times