Featured below are some of James Ensor's masks. I am unclear if he made some of the masks or if they were merely owned by him. Apparently his studio was located above a novelty shop that his family owned where masks like this were sold. Heres a great bit from a NYTimes article: "He knew all the right art-world people but hated most of them and was sure they hated him. He was an aggrieved traditionalist with a pop-culture itch, equally entertained by Rubens and tabloid cartoons. He was a sophisticated artist who helped shape early Modernism, not in a Paris studio but in an attic room over a novelty shop in a resort town on the North Sea." (source) I had trouble finding one good website for the mask images so the collection below comes from a wide variety of individual photos on pinterest, flickr, etc. - Thanks to the individuals who posted these gems.
Some countries actually put ARTISTS on their banknotes! This is a banknote from Belgium featuring the artist with some of his masks. Would the United States ever put an artist on their currency? See also Giacometti on Swiss banknotes.