Did Albert Camus, author of The Stranger, believe that life was meaningless?

Yes, but also no.

Camus was an existentialist, but he was also a part of a subset of existentialists called the absurdists.

The philosophy of existentialism relies on the thought that life is about creating your own meaning rather than accepting meaning from somewhere else, like tradition or authority. Of course, this leads to the conclusion that the meaning of life will be unique to each one of us and that it will always...

Yes, but also no.

Camus was an existentialist, but he was also a part of a subset of existentialists called the absurdists.

The philosophy of existentialism relies on the thought that life is about creating your own meaning rather than accepting meaning from somewhere else, like tradition or authority. Of course, this leads to the conclusion that the meaning of life will be unique to each one of us and that it will always be subjective, rather than objectively true.

Absurdists like Camus take this a step further while straining the existentialist idea. The core nugget of the absurdist philosophy is that life has no inherent meaning but that existentialism still holds nevertheless: even though life is actually meaningless, that does not mean that we should kill ourselves (Camus argues against suicide in one of his books of essays, The Rebel). Instead, the lack of an inherent meaning to life actually reinforces the idea that it is up to us to create our own, strengthening the power of the existentialist ideal.

This is why Camus's line of thought is called "absurd": Life is meaningless, but nevertheless, we persevere and struggle to find one. It is also why Camus had such a strong affinity for the myth of Sisyphus, the Ancient Greek story of the man punished to eternally push a stone up a hill, only for it to roll back down. It's all pointless, but we do it anyway.