Dewey is the brains of the trio. Dewey is very smart and well-organized. Dewey loves to think of new ideas and ways to have fun. On occasion, he shows he has the talents of an inventor as well. Dewey is also shown to have leadership potential, as he took control as leader on a few occasions. He wears a blue shirt. In his teenage appearance in Quack Pack, Dewey wears a white and dark blue striped short sleeve openly baseball top with dark blue outlines and the edge of his sleeves and a number "11" at the back with a navy blue round designs in each sleeve. Underneath he wears a light blue shirt and blue pants.
In early cartoons, Dewey would sport a tangerine shirt instead of his now-trademark blue, which wouldn't appear in Dewey's animation days until DuckTales.