Is who a proper noun?

Answer 1

The word 'who' is not a noun; the word 'who' is a pronoun.

The pronoun 'who' is an interrogative pronoun, a word that introduces a question. Example:

Who gave you those flowers?

The pronoun 'who' is a relative pronoun, a word that introduces a relative clause (a group of words with a subject and a verb that gives more information about the antecedent). Example:

My neighbor who has a garden gave them to me.