Is him a common or proper noun?

Answer 1

No, the word 'him' is a pronoun; the third person (the one spoken about), singular, objective personal pronoun. The pronoun 'him' takes the place of a noun for a male as the object of a verb or a preposition. Examples:

The teacher gave him an A on his essay.

Today is dad's birthday and we made a cake for him.

A personal pronoun takes the place of a noun for a specific person or thing in a sentence.

The personal pronouns are: I, you, we, he, she, it, me, us, him, her, they, them

Answer 2

Him is not a noun. Him is a pronoun, a word that takes the place of a noun. Him can take the place of a common or proper noun. Examples:

For a common noun: My neighbor brought flowers with him when he stopped by.

For a proper noun: I really like Mark, I have a date with him.