Yoda - Frank Oz
Though he technically didn’t wear a mask, Frank Oz is unquestionably the man behind the face and movements of the puppet who plays Yoda. Lucas approached Oz’s boss, Jim Henson, to create a puppet character for “The Empire Strikes Back” (1980), but Henson was too busy with “The Muppet Show” and “The Dark Crystal” (1982). So Oz was tapped to give voice to Luke’s little green friend. Oz, who had a great deal of involvement in Yoda’s development including his signature backward speech pattern, went on to operate and voice the live-action Yoda in “Return of the Jedi” (1983) and lend his voice to the CG version of the character in all three prequels. Aside from his Yoda work, Oz is also the genius behind the Cookie Monster, Bert, Grover, Fozzie the Bear, and Miss Piggy! He’s even moonlighted as the director of such eclectic films as “Little Shop of Horrors” (1986), “Dirty Rotten Scoundrels” (1988), “Bowfinger” (1999), and “Death at a Funeral” (2007).
(Source: starwarsbehindthescenes)