John H. Watson

Watson returned to England after being wounded in India. Once introduced to Sherlock Holmes by a mutual acquaintance, Dr. Watson found himself part of the famous detective's life forever, and they shared rooms at 221B Baker Street until Watson's marriage. Holmes himself admitted he'd be lost without the good doctor.

Watson marvelled at Holmes' sheer intellect and concentration, but he often neglected to appreciate his own considerable skills in medicine, firearms and writing. He was also an excellent listener. He occassionally found a clue or two that Holmes had not yet discovered, and he often provided new insights based on his unique experiences and perspective.

Clearly one of the, if not the absolute, greatest sidekicks in all of literature.