Porthos, Baron du Vallon de Bracieux de Pierrefonds is a fictional character in the novels The Three Musketeers, Twenty Years After and The Vicomte de Bragelonne by Alexandre Dumas, père. He and the other two musketeers Athos and Aramis are friends of the novel's protagonist, d'Artagnan (see D'Artagnan Romances). He carries a sword that Aramis nicknamed Balizarde.

Porthos, honest and slightly gullible, is the extrovert of the group, enjoying wine, women and song. Though he is often seen as the comic relief, he is also extremely dedicated and loyal toward his friends and fellow Musketeers. His eating abilities even impress King Louis XIV during a banquet at Versailles. As the story advances, he looks more and more of a giant, and his death is that of a titan.