The works of Harryhausen really hold a place in my heart. Saw
7th Voyage of Sinbad, Jason and the Argonauts, Valley of the Gwangi, and
Clash of the Titans when I was still a little kid (why exactly we had VHS tapes of all those movies lying around is still something of a mystery to me), and they both captured my imagination and, since I watched them at such a young age, helped form my whole paradigm of movies.
I'm probably the only person still living who's whole paradigm of dinosaurs was shaped by
Valley of the Gwangi rather than
Jurassic Park.

Also, a word of special commendation in the area of stop-motion must be said for all the Rankin-Bass works, particularly
The Year Without A Santa Claus and
Rudolf The Red-Nosed Reindeer.