The 200th book in the series -- "SAS: The Kremlin's Revenge" -- was released last month.
Instantly recognisable by their lurid covers inevitably featuring a femme fatale brandishing a handgun or assault rifle, his work was shunned by France's literary establishment.
But outside literary circles, De Villiers was often praised for his geopolitical insights and was known for cultivating a vast network of intelligence officials, diplomats and journalists who fed him information.
In a profile early this year headlined "The Spy Novelist Who Knows Too Much", The New York Times said his books were "ahead of the news" and "regularly contain information about terror plots, espionage and wars that has never appeared elsewhere".
His death came as he seemed on the verge of realising a long-cherished dream of breaking into the English-language market, with reports he was working on a deal with a major US publisher.
In an interview with newspaper Le Monde this summer, De Villiers said Random House had offered him $350,000 (260,000 euros) for the rights to five SAS books that would be translated into English. He said he hoped the deal would eventually lead to Hollywood films.
De Villiers gleaned much of his information from field trips around the world, giving credence to the exploits of his aristocratic Austrian hero, Malko Linge, who works as a freelance agent for the CIA to fund the restoration of his family chateau.
The books stuck to a well-trod formula -- fast-moving plots, exotic locales and generous doses of graphic sex.
"I never had any pretensions of being a literary writer," De Villiers told AFP in an interview this year. "I consider myself a storyteller who writes to amuse people."
He was also considered eerily prophetic, detailing a plot to kill the Egyptian president Anwar Sadat a year before his actual assassination in 1981 and describing a secret CIA command centre in the Libyan city of Benghazi in early 2012.
The true existence of the CIA site eventually came to light after an attack on US facilities in Benghazi in September 2012 that left four dead, including US ambassador Christopher Stevens.
His work was reportedly required reading in some intelligence circles and followed by spies far outside France.
"The (intelligence) services used SAS novels countless times to send messages to their counterparts," said De Villiers's longtime lawyer, Eric Morain.
Born in Paris on December 8, 1929, De Villiers was working as a journalist when he drew inspiration from the success of Ian Fleming's James Bond series to write his first novel, "SAS in Istanbul", in 1965.
He went on to publish an average of four SAS novels -- so-called after Linge's honorific "Son Altesse Serenissime" (His Most Serene Highness) -- every year, writing them over a month on an aged typewriter.
He was often lambasted for his right-wing views and his overtly sexual portrayals of women, and accused of racism.
But De Villiers was unapologetic.
"Some women are sexual objects in my books but others are beautiful, intelligent and brave. And I am always warmly welcomed in Africa, where I have very many readers," he said.
De Villiers's wife Christine said he had been undergoing treatment for pancreatic cancer since May.
"The last weeks he was conscious but very weak. He could not endure the chemotherapy," she told AFP. "It is exactly the death that he did not want."