Thanks to the Cleric, who pointed me in the direction of this picture on Facebook. It's Dr. Gayle Dine'Chacon, Surgeon General of the Navajo Nation, posing with Johnny Depp in his Tonto costume on the set of The Lone Ranger. Interestingly he looks way less ridiculous here than he did in the first official still, but the poster made the joke that Dr. Dine'Chacon was 'called out to give medical attention to that crow on Johnny Depp's head.'
Depp poses with a fan in his sidekick garb.
Source: The Cleric