Born in Los Angeles in 1920, Harryhausen was inspired by the work of Willis O'Brien on films like 1925's The Lost World and the 1933 version of King Kong.
O'Brien mentored Harryhausen, who then went to work for Oscar-winning director Frank Capra. After the second world war, he made stop-motion versions of fairy tales - his work was spotted, and he was hired to work on the ape in the 1949 movie Mighty Joe Young with O'Brian.
Harryhausen's best known work was on the 1981 film Clash of the Titans. An animated battle with skeletons took three months' work.
I was moved by his death on a personal level. I met him while I was at the Academy of Art University, in the US. A kind man in his late 70s, he showed me the original models for Titans and other films.
I handed him a model of his famous skeleton warriors from Jason and the Argonauts, which he signed, saying: "I didn't even know these were made."
As he later explained in his lecture, the film studios owned the rights to all of his creations, and could do what they liked with them.
He was a genius, admired by many filmmakers, including Steven Spielberg and James Cameron. He'll be missed.