Diego the Dreadful was a Spanish pirate who appeared in The Secret of the Unicorn in The Adventures of Tintin series he is first seen as he challenged Sir Francis Haddock in a duel. As Archibald Haddock was role-playing Sir Francis, he was now revealed as he was stabbed on the belly, when Archibald stabbed his pillow cushion and Red Rackham explaining to the captured Sir Francis that he Sir Francis killed Diego.