Who does 'you' refer to in sonnet 55 line 3 (not marble, nor guilded monuments)?

The poet never reveals who exactly "you" is referring to. It is a "fair lord". It is part of Shakespeare's "fair youth" sequence of sonnets (1-122) where he refers to a young man. Shakespeare was considered bi-sexual if not homosexual. Many critics believe that Shakespeare had a major thing for the Earl of Southampton to which these sonnets might have been dedicated to.

you refers to the poets beloved......................