Meursault is a French Algerian who learns of his mother's death by telegram. Meursault's indifference to the news of his mother's death demonstrates some emotional detachment from his environment. There are multiple instances throughout the novel where significant moments do not have an emotional impact on Meursault. He doesn't show emotion to the fact that his mother is dead, Marie loves him or that he killed an Arab. Another aspect of Meursault is that he is an honest person. He always speaks his mind and does not care how other people see him. He is regarded as a stranger to society due to his indifference.
Raymond Sintes is the neighbor of Meursault who beats his mistress which causes a conflict with the Arabs. He brings Meursault into the conflict which ultimately results in Meursault killing the Arab. Raymond can be a foil character of Meursault in that he takes action while Meursault is indifferent. Raymond and Meursault seem to develop a bond as the story goes on and ends with Raymond Sintes testifying for Meursault during his trial. Raymond also views things on what he owns- he assaults a woman because she cheated and he insists Meursault is his friend after a simple favor from Meursault.
Marie Cardona was a typist in the same workplace as Meursault. A day after Meursault's mother's funeral she meets him at a public beach which sparks their relationship. She asks if Meursault loves her but Meursault replies that he doesn't think so. He still agrees to marry her but he gets arrested for killing the Arab. Marie, like Meursault, enjoys physical contact in their relationship through the act of sex. She represents the enjoyable life Meursault wants and she is also the only reason that Meursault regrets going to jail.
Masson is the owner of the beach house where Raymond takes Marie and Meursault. Masson is a carefree person who simply likes to live his life and be happy. He wants to live life without restrictions.
Salamano is an old man who beats his dog and routinely takes it out for walks. He ends up losing his dog and asks Meursault for advice. Meursault does not offer helpful advice and Salamano acknowledges that his life has changed.