King Kong is special because it gets the idea of adventure. There's a perfect sort of magic surrounding that lost island filled with dinosaurs that somehow survived whatever happened to the rest of the world and I always used to wonder (and maybe hope a little) that that place really existed.
The List So Far:
1927 - Metropolis - Fritz Lang
1928 - Steamboat Willie - Ub Iwerks
1931 - M - Fritz Lang
1932 - Tarzan, The Ape Man - W. S. Van Dyke
1933 - King Kong - Merian C. Cooper +