Through retellings, additions, and variations a body of familiar characters associated with Robin Hood have been created. These include his lover, Maid Marian, his band of outlaws, the Merry Men, and his chief opponent, the Sheriff of Nottingham. The Sheriff is often depicted as assisting Prince John in usurping the rightful but absent King Richard, to whom Robin Hood remains loyal. A common theme of the story is that Robin is a champion of the common people fighting against injustice, whilst remaining loyal to the rightful ruler. He became a popular folk figure in the Late Middle Ages, and the earliest known ballads featuring him are from the 15th century.

What is the theme of the story of robin hood? OK. Let's think. My stream of consciousness:
The relevant sentence in the passage is: A common theme of the story is that Robin is a champion of the common people fighting against injustice, whilst remaining loyal to the rightful ruler. The answer is Robin is a champion of the common people fighting against injustice , whilst remaining loyal to the rightful ruler.