The term 'HERO WITH A MASK' can be summarized by the crossword solution of 'BATMAN', a 6 letter word. BATMAN is a fictional superhero created by artist Bob Kane and writer Bill Finger, who first appeared in Detective Comics #27 in 1939. He is a vigilante who fights crime in Gotham City while wearing a mask to conceal his identity. BATMAN is one of the most iconic and popular superheroes in comic book history.