In real life, Athos' name was Armand de Sillègue d'Athos d'Auteveille. He is the Musketeer most lost to history. His family is known for their holding of Athos-Aspis from which Athos took his name. Armand was the cousin of Troisvilles (Captain Treville) and through Troisvilles' influence became a Musketeer. The only other thing we know definitely about Armand is that he died in Paris on the 21st of December, 1643, aged in his twenties. It is possible that he was a victim of a robbery or some other violent crime, as in his obituary, he is described as having been "taken". There is no guarantee that in real life he knew d'Artagnan, Aramis, or Porthos.