Charles Ogier de Batz de Castelmore, Comte d'Artagnan served Louis XIV as captain of the Musketeers of the Guard and died at the Siege of Maastricht in the Franco-Dutch War. A fictionalized account of his life by Gatien de Courtilz de Sandras formed the basis for the d'Artagnan Romances of Alexandre Dumas, most famously including The Three Musketeers. The heavily fictionalized version of d'Artagnan featured in Dumas' works and their subsequent screen adaptations is now far more widely known than the real historical figure.
The oldest by some years, Athos is a father figure to the other musketeers. He is described as noble and handsome but also very secretive, drowning his secret sorrows in drink. He is very protective of d'Artagnan, the youngest, whom he regards as a son.
Athos' first name is never told. However, in Dumas' play "The Youth of the Musketeers," the young Milady, then named Charlotte, calls the then Vicomte de la Fère, Olivier, so one may assume that this is Athos' first name.