If the name Ray Harryhausen means nothing to you, you must either be quite young or simply don't pay attention to film credits. He is gone now but until recently was THE foremost expert on stop-motion animation and its attendant special effects. As such, he was paid homage in Pixar's Monsters, Inc., wherein an upscale restaurant was named after him.
He apprenticed under Willis J. O'Brien, the genius behind 1933's King Kong. He later came into his own and was responsible for the visual effects in 1963's Jason and the Argonauts, embedded below, and 1981's Clash of the Titans, among many others.
He kept the many of the articulated models used in filming and these have been restored to as-new working condition. Their story can be found here.
I saw his film Jason and the Argonauts in the theater and was amazed. Of course, I was only 11 years old at the time. But his work stands up well even in this age of CGI; look at the site referenced and then view the embedded film. How much time and effort must that have taken to film all that? Short answer: Quite a lot.