Tonto, the Lone Ranger's Indian companion originally rode double with the Lone Ranger on the Lone Ranger's horse. Ouch for the horse! In time, the studio gave Tonto his own horse, another solid white horse. The television powers felt it was confusing to have two solid white horses, so they evolved to a palamino horse for Tonto.

Tonto's horse had several previous names: White Feller, Paint Horse and Paint.

The television powers finally decided that Tonto's horse would be named Scout, the final name for Tonto's horse. Hi yo Scout!

More Info: en.m.wikipedia.org