D'ArtagnanA young man from Gascony who leaves his family to join the King's Musketeers. He ends up becoming friends with the Three Musketeers and soon joins them on their various adventures and becomes involved with the intrigues of the royal court.
Athos aka the Comte de La FereThe oldest of the Musketeers. He is melancholy and stoic yet becomes a sort of father figure to d'Artagnan. He is actually a nobleman and was married to Milady de Winter yet tried (and failed) to hang her after he discovered that she was branded as a thief. He has a son named Raoul in the later books who he is very fond of.
PorthosOne of the Musketeers. A strong but simple fellow who forms perhaps the emotional core of the Musketeers.
Aramis a k a René d'HerblayThe last of the Musketeers, Aramis originally intended to join the priesthood but ended up as a soldier after he got into a fight with another man. He is scholarly and provides common sense for the other three. In the later books he does become a priest and then later Bishop of Vannes. He also attempts to have Louis XVI replaced with his identical twin brother.
GrimaudAthos' valet. Athos ordered Grimaud to speak only in emergencies and generally only communicates through sing language.
Milady de WinterA seductive spy who works for Cardinal Richelieu. She is involved in first the plot with the Queen's diamonds and then in the assassination attempt on the Duke of Buckingham. She turns out to be Athos' wife who he thought was dead.
Cardinal RichelieuThe scheming minister of Louis XIII who plans to expose the Queen's involvement with the Duke of Buckingham. He organizes the death of Buckingham for the greater good of France.
Louis XIIIThe capricious King of France in the first book who wages war against the Protestants at La Rochelle and suspects that his wife is having an affair with the Duke of Buckingham.
Anne of AustriaThe Queen of France. She is suspected of having an affair with Buckingham and is nearly brought down by Milady and the Cardinal. After Louis XIII's death, she becomes Queen Consort to her son Louis XIV, ruling jointly with Cardinal Mazarin (who she also marries secretly).
George Villiers, the Duke of BuckinghamThe first minister of England who aids the Protestants at La Rochelle. He woos Anne of Austria and, as such, jeopardizes France because this allows Cardinal Richelieu to try and discredit the Queen. Thanks to Milady, he is murdered by John Felton.