Robin Hood is a British folk hero who is immortalised in countless movies, books and TV series. Over the centuries his story has been told many different ways but a common theme is that he robs from the rich (represented by the corrupt Sheriff of Nottingham) to give to the poor, making him a symbol of resistance against injustice.

As he dates from the 14th century, he is a public domain character and should be completely safe to use from a copyright perspective.

I think this could be a popular UK exclusive premium stamp.