Matthew Carpenter is the third child and second son of Michael and Charity Carpenter. He first appears in Death Masks.
In Death Masks, Harry Dresden sees Matthew return to the Carpenter home with Daniel Carpenter and Alicia Carpenter as he is leaving to prepare for a duel.
In Small Favor, the Carpenter family and Harry Dresden are having a snowball fight when three gruffs attack. Molly veils Matthew and Alicia and they manage to retreat inside the house.