Amelia Fieldmouse is Mickey Mouse's sister, also Oswald the Lucky Rabbit's half-sister and the mother of Morty and Ferdie Fieldmouse.
The character first appeared in Morty and Ferdie's 1932 comics debut. In the English version of these comic strips, she is referred to only as "Mrs. Fieldmouse." In the Dutch translation of the strips, her name is given as Amalia. In various English language references, this is typically Anglicized to Amelia Fieldmouse. The original strips do not make clear that Amelia is Mickey's sister; as drawn, she looks more like a maiden aunt. But the relationship has been clarified when she reappeared in more recent comics. At Egmont Publishing, Amelia's name is given as "Felicity Fieldmouse". As a side note, Egmont also named Felicity's husband—the twins' father—Frank, though he has yet to be specifically named or depicted in a published comic. Egmont's modern version of Amelia has slimmed down and is designed to look closer to Mickey in age, while remaining significantly taller than him.