If you know who he was, then you know his work in the early days of movie special effects.
A long list of his accomplishments can be found at http://www.rayharryhausen.com
It is my belief that he should be made an unofficial Patron Saint of Model Builders and Miniature Painters.
My personal favorite of his creation is the Medusa from 'Clash of the Titans'. Does anyone else have a favorite monster or memorable movie moment?