Ownership of films is usually the preserve of directors and actors. You will hear of the new Paul Thomas Anderson movie, or the new Tom Cruise vehicle. But such films as The 7th Voyage of Sinbad, (1958), Jason and the Argonauts (1963)and Clash of the Titans (1981) are Ray Harryhausen films, regardless of who directed and acted in them. One Million Years BC, a film for which, unusually in his career, he was brought in as a hired hand, (1966) isn't even regarded as a Hammer or Raquel Welch movie. No other technician or artist working in film can make such a claim.

"Everyone has their own right way of doing things," explains Harryhausen, now aged 92. "I'd probably call myself a film-maker rather than just a special effects man. I'd often come up with the story, advise on the script, scout locations, design and sculpt the models. I'd have to be on the set to make sure the effects sequences were shot properly which was a problem for some directors – that never really got easier. And I'd do all the animation myself. It was just simpler to do all that myself than try to delgate."

As a result, all Harryhausen films have his personality, and his incredible craftsmanship, showing through them. I meet him in the Kensington house he and his wife Diana have shared since he moved his base of operations from Hollywood to Europe almost half a century ago. "I dread to think what it would cost now," he says. "We found out from some neighbours many years later that Michael Powell used to own this house. He had a pair of red shoes hanging in one of the windows."

Harryhausen's home has no such external signs of its inhabitant's career. Inside there are few clues among the antique furniture. Until, that is, you take a closer look at the bronze sculptures on display. There is the Hindu goddess Kali, an allosaurus, some sword-wielding skeletons (a dead giveaway), Perseus and Medusa locked in deadly combat. "That one was used to show to studios when we were getting Clash of the Titans going," Harryhausen explains. It is common for artwork and even test footage to be used to generate interest in a film, but this is the first time I have heard of a piece of bronze being used to sell a project.

Harryhausen with a life-size replica of Medusa from Clash of the Titans at the London Film Museum. Photograph: Matt LLoyd / Rex Features

One of the most dramatic of his self-made ornaments is of a T-rex and King Kong. For Harryhausen it was Kong that started it all, back in 1933. "I had an aunt who took me to see a new movie she'd heard had gorillas and dinosaurs in, two things I was very much interested in." She took the 13-year-old Harryhausen to Grauman's Chinese Theater on Hollywood Boulevard to see King Kong on its opening week in LA, a night filled with the sort of showmanship typical of the venue's owner Sid Grauman. The foyer was decorated in jungle style, and music and dance acts performed before the curtain went up for the film. With that set up followed by a film unlike any seen before the evening delivered the kind of sensory overload that beats things like 3-D and IMAX into a cocked hat. Harryhausen left the cinema with no idea how this lost world had been created, but he knew that he had to find out.

"I wasn't even looking to get into movies. I was a diorama kid at school, always making these little prehistoric scenes. Well, here was a way to make my dioramas move. I knew it wasn't a man in a suit. There was a magazine article that even had a picture of a life-size Kong with electrical leads running out of it. Even at that age I knew that couldn't be true. It wasn't like today: information was almost impossible to find." He pieced together what few facts he could and started making his own crude attempts with a home-movie camera.

Harryhausen took evening classes to learn and refine the skills he felt he would need, such as sculpture, engineering and photography. "I took some acting classes, but that wasn't really me, although I did learn about movement and building character." Character is the key to why his creations endure: often they give better, or at least more memorable, performances than the human actors. It's clear where Harryhausen's sympathies lie in this regard. "The Cyclops (from 7th Voyage Of Sinbad) wasn't bad, he was just trying to get back what was his from these people who came and stole from him." He even used his drafting into the army to further his craft. "I thought I could be a combat photographer, but quickly found out that they were getting sent to the front lines in places like Iwo Jima and getting killed along with everyone else. I'd made a short animated film showing the construction of a military bridge so I ended up making training films for the Signal Corps." This also enabled him to get access to more professional equipment: "The Hollywood studios contributed a lot of their resources to the war effort."

He'd also managed to track down the man behind the magic of King Kong, Willis O'Brien. "Obie was very critical of my little dinosaur puppets, but very helpful, he taught me so much," Harryhausen says. "He got me to study anatomy. When it came time for him to do Mighty Joe Young I was his assistant and ended up doing about 90% of the actual animation."

He soon met a producing partner with whom he enjoyed a long working relationship career, Charles H Schneer. "Charlie was very important in all this. He made these projects in a way that let me do all these things no other producer would or could," Harryhausen says. Their partnership lasted 30 years and 11 films, including 20 Million Miles to Earth (1957), Mysterious Island (1961), The Valley of Gwangi (1969) and three Sinbad films. During this time Harryhausen developed his Dynamation technique, involving split-screens and rear-projection, for inserting his models into live-action footage. They soon found Hollywood too restrictive ("The unions wouldn't let me even move the camera or lights, that would be other people's jobs. And there are only so many films you can make in the desert around California.") In moving to London, Harryhausen had access to locations in Spain, Malta and Greece as well as "the wonderful British film studios and technicians, easily as good as anything in Hollywood."

The importance of these films cannot be overstated. The new documentary Ray Harryhausen: Special Effects Titan features contributions from film-makers such as James Cameron, George Lucas, Terry Gilliam, Henry Selick, Tim Burton, Peter Jackson, John Landis and Nick Park, all with a common story of how these films inspired them. Harryhausen's work kept fantasy film-making alive through tough times. His legacy is seen in some of the biggest-grossing films of all time, made by people who were just kids when they first saw his work. "We are all children of the Hydra's teeth," as seven-time Oscar-winning makeup artist Rick Baker put it at Harryhausen's 90th birthday bash at the BFI two years ago, an event where dozens of key names in film-making flew over to the UK on their own dime, this is the level of regard and adoration the man is held in.

Harryhausen still displays an enthusiasm for the fantasy genre that people a quarter of his age seldom match as he talks about film-makers he's admired such as George Pal and Karel Zeman, as well as animators who've impressed him like Randy Cook, Jim Danforth and, of course, Willis O'Brien. Animation is still a tool widely used today. Movies such as Frankenweenie, ParaNorman and Pirates! all do big business and charm audiences worldwide. With huge networks of fantasy and science fiction fans and massive conventions prevalent today, it is humbling to think where all this started, back in 1940s California: "In those days it'd just be me, [lifelong friend] Ray Bradbury and Forrest J Ackerman (later editor of Famous Monster of Filmland magazine) huddled together in a diner discussing things like space platforms and dinosaurs. We each did, and usually accomplished, what we set out to do. Though people thought we were very strange."

• Ray Harryhausen: Special Effects Titan is released in the UK on 9 November