Morty and Ferdie Fieldmouse are Mickey Mouse's nephews in the fictional Mickey Mouse universe. They first appeared in the Mickey Mouse comic strip titled Mickey's Nephews in 1932. Since then they have appeared in lots of comic strips and comic book stories starring Mickey Mouse and Pluto.

In books (not comics) produced by the Disney studios about Mickey and his gang they were usually called Morty and Monty rather than Morty and Ferdie. Very early books contain three or more nephews with various names.

Their first film appearance was the Mickey Mouse cartoon titled The Steamroller. They didn't appear in animation again until Mickey's Christmas Carol. Then they made a cameo appearance in a two part Mickey Mouse Works segment titled Around the World in Eighty Days which was recently reused on an episode of House of Mouse. In some comic book stories from other countries their mother is named Amelia Fieldmouse, sister of Mickey.

Ferdie disappeared from the Floyd Gottfredson comic strip because Gottfiedson thought the nephews were too much alike. He had plans to bring Ferdie back later as an bespeckled intellectual, bookworm boy mouse with Eton hat and coat with the explanation that he had been away at school. But Gottfredson never got around to bringing Ferdie back and Morty remained in the strip alone.