Porthos, Baron du Vallon de Bracieux de Pierrefonds (his first name is unknown) 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.
In The Three Musketeers his family name is du Vallon. In Twenty Years After, after a successful wedding, he is first known as du Vallon de Bracieux de Pierrefonds, then he earns the title of baron
Porthos, honest and slightly gullible, is the extrovert of the group, enjoying wine, women and song. 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.
At the time of The Three Musketeers (ca. 1627) he apparently has few lands or other resources to draw from. He was finally able to extract sufficient funds from an elderly lawyer's somewhat younger wife (whom he was romancing) to equip himself for the Siege of La Rochelle.
The fictional Porthos is very loosely based on the historical musketeer Isaac de Porthau.