The Three Musketeers (French: Les Trois Mousquetaires) is a novel by Alexandre Dumas, pere. Set in the seventeenth century, it recounts the adventures of a young man named d'Artagnan after he leaves home to become a guard of the musketeers. D'Artagnan is not one of the musketeers of the title; those are his friends Athos, Porthos, and Aramis; inseparable friends who live by the motto "all for one, one for all" ("tous pour un, un pour tous").
The story of d'Artagnan is continued in Twenty Years After and The Vicomte de Bragelonne. Those three novels by Dumas are together known as the d'Artagnan Romances.
The Three Musketeers was first published in serial form in the magazine Le Siecle between March and July 1844.