The [original Lone Ranger] radio series identified Tonto as a chief's son in the Potawatomi nation. His name translates as "wild one" in his own language. For the most part, the Potawatomi did not live in the Southwestern states, and their regalia is different from that worn by Tonto. The choice to make Tonto a Potawatomi seems to come from station owner George Trendle's youth in Mullett Lake, Michigan. Located in the northern part of the Midwest, Michigan is the traditional territory of the Potawatomi, and many local institutions use Potawatomi names. Other sources indicate that Camp Kee Mo Sah Bee belonged to the father-in-law of the show's director, James Jewell. According to author David Rothel, who interviewed Jewell a few months before his death Kee Mo Sah Bee and Tonto were the only two words that Jewell remembered from those days. Tonto's name may have been inspired by the name of Tonto Basin, Arizona.
"Tonto" is also a common Spanish and Italian word meaning "stupid." Interestingly, "Kee Mo Sabe" comes pretty close to "que no sabe," roughly Spanish for "clueless one" (i.e. "tonto"). Source.
I’d actually seen a painting by an artist named Kirby Sattler, and looked at the face of this warrior and thought: ‘That’s it’. The stripes down the face and across the eyes… it seemed to me like you could almost see the separate sections of the individual, if you know what I mean. There’s this very wise quarter, a very tortured and hurt section, an angry and rageful section, and a very understanding and unique side. I saw these parts, almost like dissecting a brain, these silvers of the individual. That makeup inspired me. ~ Johnny Depp