As the main archenemy of Bond, Blofeld can be found in several novels and movies.
Squaring off face-to-face for the first time in "You Only Live Twice" (1967) (previously we either hear him and see his hand stroking his cat), he's played by Donald Pleasence. Though SPECTRE's number one is played by others in future films — including Telly Savalas, Max von Sydow, and most recently Christoph Waltz — Pleasence has the part down perfectly in his portrayal.
The menacing look, the petting of the white cat, he's the best of all the Blofelds.