The 74-year-old keyboard-player had been suffering from bile duct cancer.
Manzarek was gigging up until February in support of his third collaboration with producer and guitarist Roy Rogers, Twisted Tales.
His fellow Doors member, guitarist and long-time collaborator, Robby Krieger said: "I was deeply saddened to hear about the passing of my friend and bandmate Ray Manzarek today. I'm just glad to have been able to have played Doors songs with him for the last decade. Ray was a huge part of my life and I will always miss him."
The musicianly tributes have already started to flood in with ex-Inspiral Carpets man Clint Boon speaking for many when he says: “Ray Manzarek, you were unbeatable. I could never imagine the world without you in it. Thank you for everything. Rest in peace brother.”
Royseven’s Paul Walsh adds: “Rest in Peace to Ray Manzarek, keyboard-player with The Doors, my favourite band growing up.”
Luke Haines tweets: “I love The Doors, 'An existential bar band' in Big Jim's own words. Fantastic group. God bless you Ray Manzarek.”
The Riptide Movement say: “This is the end, beautiful friend. Rest in peace Ray” while "RIP Ray Manzarek, words cannot express,” is the message from a distraught Slash.
Elektra Records: “Today we bow our heads in respect of the passing of Ray Manzarek, keyboardist of The Doors. A man who changed the face of music, and Elektra.”
Robbie Krieger: “I was deeply saddened to hear about the passing of my friend and bandmate Ray Manzarek today. I'm just glad to have been able to have played Doors songs with him for the last decade. Ray was a huge part of my life and I will always miss him."
Flea: "Wow. Ray Manzarek. Bless his heart. One of a kind rock original. Grateful to have jammed with him once. RIP."
Carl Barat: “Aw, I loved Ray Manzarek. He wrote the soundtrack to so many epiphanies. RIP Brother Ray.”
The Minutes: “So long Ray. Morrison Hotel now on repeat.”
De La Soul: "R.I.P. Ray Manzarek... The keys to The Doors."
Maureen Van Zandt: “Sad to hear that Ray Manzarek has passed away. And so sad to hear the news from Oklahoma. Heartbreaking.”
Billy Idol: "Sad to hear about Ray Manzarek passing. I was lucky to get a chance to rock out with him & the other two Doors... Cheers mate, say hi to Jim."
Krist Novoselic: "Thanks for the great music Ray Manzarek!"
Matt Sorum: "Ray Manzarek RIP. So honored to have known him and played with him. A genius."
John Densmore: "There was no keyboard player on the planet more appropriate to support Jim Morrison's words. Ray, I felt totally in sync with you musically. It was like we were of one mind, holding down the foundation for Robby and Jim to float on top of. I will miss my musical brother."
Simon Le Bon: "Very sad to hear of the death of Ray Manzarek, founder & keyboards with The Doors. Played a Fender Rhodes like some funked up Bach."
Alice Cooper: "Absolutely stunned by the loss of my old friend Ray Manzarek of The Doors... Stunned. RIP Ray."
Paul Shaffer: "The sound of Ray Manzarek's organ will forever reverberate in the cathedral of Rock and Roll."
Chuck D: "RIP Ray Manzarek of the DOORS!"
Peter Hook: "Very sad to hear of the passing of Ray Manzarek - The Doors were a huge influence on all of us when we started out, especially on Ian. RIP."
Skrillex: "Wanted to thank my dad who would always play the Doors while I was growing up. 'Riders On The Storm' was my favorite as a child."