Dewey is a character in Malcolm In The Middle, played by Erik Per Sullivan (151 episodes) and Caleb Ellsworth-Clark (4 episodes), is portrayed as being the quieter, more innocent brother but becomes just as spiteful and destructive as his older siblings as the series progressed. Initially the youngest brother, Dewey is regularly bullied by both Malcolm and Reese for years to the point where he becomes completely immune to their torture methods. He is also frequently underestimated by his brothers to the point where they sometimes find themselves at his mercy. Despite this, he partakes in many of the brothers' juvenile schemes and is just as spiteful and vindictive as they are. Dewey is more inclined to the arts than his brothers. He soon finds he is a musical prodigy, and as the series goes on he becomes more caring and thoughtful especially in regards to his younger brother Jamie, whom he decides not to bully like he was by Malcolm and Reese.
In the revival series, he is shown to be spending a lot of time touring the world as a successful musician.