A sidekick is a close companion who is generally regarded as subordinate to the one he accompanies. Some well-known fictional sidekicks are Don Quixote's Sancho Panza, Sherlock Holmes' Doctor Watson, The Lone Ranger's Tonto, The Green Hornet's Kato, Munna Bhai's Circuit and Batman's Robin.
Read more about Sidekick: Origins, Function of The Sidekick, Comparisons, Use in Fiction, In Television