Ray Harryhausen (1920-2013) was an American artist, designer, visual effects creator, writer and producer who created a form of stop-motion model animation known as "Dynamation".
When asked what film segment Harryhausen was most proud of, he said he was proud of all his work but,
“the skeleton segment in Jason and the Argonauts gives me the greatest satisfaction. It was certainly the most time-consuming and elaborate sequence I ever designed.”
Watch the video; Harryhausen's work in one of the most recognisable sequences of film history.