From what I’ve read so far, I believe that Meursault is the stranger. A stranger is someone who is an outsider or a foreigner and I noticed that Meursault is a stranger to society and somewhat himself.
He doesn’t follow social norms. He didn’t show compassion for his mother, Raymond’s girlfriends, Salamano’s dog, etc. In the eyes of society, his kind of behavior is regarded as bizarre. Meursault does not understand why events have a sentimental value for people and this is what makes him disconnected with society. In addition, I think that he is a stranger to himself in a way, but not more than he is to others. He goes through events without a plan and without commitment to either principles or people. He doesn’t know who he is and he doesn’t care. Meursault is a stranger and an absurdity to society because he does not show any emotions, he has no meaning for life, and his only certainty and guarantee is death.