Perry the Platypus

Perry is a blue-green platypus with tangerine-colored webbing that has yellow tints only on his hind feet (curious features that platypuses outside of Danville don't have). He also has three dark hairs on his head, a long, low-set, salmon-orange beaver tail, dark brown eyes in an oddly cross-eyed position, giving him an ignorant look, and a duck-like bill that matches the color of his webbing. Under his fur, he also has a locket shaped like his webbed feet that displays three photos of him and his owners, Phineas and Ferb.

When Perry is no longer undercover, he stands on his hind legs, his front paws resemble hands, and he wears a brown fedora hat that agents use as a "spy uniform".