Si Nonymouse, better known as Miss Quackfaster, is a male anthropomorphic mouse.
Si Nonymouse is a well-respected art dealer with an outgoing personality. Nonymouse appears to think little of classical figurative art, and is instead crazy about modern abstract pieces. In 2011, Emily Quackfaster invited Nonymouse to the Money Bin on Scrooge McDuck's behalf, trying to get Scrooge to adorn the bleak offices of the Bin with some paintings. Horrified at the price offered by Nonymouse, and ruling that he could easily do better than the paintings Nonymouse offered, Scrooge went to the countryside to try and paint a picture of his own. The canvas ended up a complete mess after a series of slapstick incidents, but Nonymouse, who saw it by pure chance, immediately bought it for a hefty sum, claiming it was a work of pure genius.