His sudden and untimely death at the age of 27 stunned fans of The Doors, who broke fresh ground in psychedelic rock with such hits as "Riders on the Storm," "People are Strange" and "Light My Fire".
There was never an autopsy, giving rise to multiple conspiracy theories, as Morrison's remains were buried at Pere Lachaise cemetery, final resting place of other such notables as Marcel Proust, Gertrude Stein and Oscar Wilde.
Two of his bandmates, keyboardist Ray Manzarek and guitarist Robby Krieger, will mark the anniversary with a sell-out concert at the Bataclan club, while a tribute band from Britain, The Doors Alive, will perform at the Cigale.
That Pere Lachaise is reputedly the most-visited cemetery in the world is due in no small part to the crowds that flock every day to visit Morrison's flower-strewn gravestone.
"James Douglas Morrison, 1943-1971," reads a plaque on the gravestone erected in the 1990s by the singer-poet's father, who added a Greek phrase often interpreted as "true to his own spirit".
"I've listened to his music intensely since I was a kid," said Alex, an American in his fifties living in Paris recently seen humming another Doors classic, "The End", as he came by to pay his respects.
"When I was 15 years old, I adored him. His lyrics were so profound. He had a genuine fascination with death, like a self-fulfilling prophecy," he told AFP.
"Morrison, that's my youth," said Gunther, 54, who expressly came from Germany to visit the grave that is under constant surveillance against degradation. "Being here brings back so many memories from that time."
But the most fervent pilgrims were not even born when Morrison died. Having discovered The Doors through their parents' record collections, they see in his legacy an image of what rock'n'roll had been in its heyday.
"I'm 17 and I've been listening to The Doors since I was three," said Jay Stanley, visiting Paris with a school group from the United States. "He personifies America. He's my idol. I have posters of him all over my room."
In skinny jeans and a Doors T-shirt, Maria, 27, from Russia, said: "He's the father of rock'n'roll. I love his music and mysticism. For all my life I wanted to visit his grave. Now I have."
Morrison, whose nickname grew out of a poem, "Celebration of the Lizard", moved to Paris after the 1971 release of "L.A. Woman" and lived in the then-not-yet-hip Marais district with partner Pamela Coulson.
It was she who found him dead, with a heart attack officially cited as the cause. His death was made public two days after he was buried at Pere Lachaise attended by just five people.
Conspiracy theories abound, however, including one from a British journalist in the 1980s who pointed a finger at the US Central Intelligence Agency.
In a 2007 book, rock writer Sam Bernett asserted that Morrison in fact died in the washroom of a Paris nightclub, the Rock'n'Roll Circus, apparently from an overdose.
Bernett, who managed the venue, said that a couple of drug pushers dragged the body into a taxi and returned it to the apartment. The proprietor never told police what transpired, he added, for fear of igniting a scandal.
Manzarek, who has done much to keep the Doors flame burning, once suggested another possibility. Recalling a 1970 conversation with Morrison, he wondered if the intense frontman had just faked his death to start a new life incognito.
Coulson herself died of a drug overdose in Los Angeles in 1974.