My question is very concise, please forgive it.

Who introduced the concept of ringed space?

My first try would be that they were introduced by Cartan in his study of analytic functions with sheaves. I do not know if there is a reference for my supposition or if they were introduced before.

Do you know something about this?

implicitin the work of Cartan. The question though is why would one need to introduce ringed spaces? The answer, I think, is because one wants to know what the morphisms are. In the classical setting of manifolds or varieties, it is clear what the morphisms are. For schemes, however, one needs to introduce the category of (locally) ringed spaces first. So I would guess (and it is really just that) the answer is Grothendieck. $\endgroup$