Is poet a proper or common noun?

The noun 'poet' is a common noun, a general term for anyone who writes poetry of any kind.

A proper noun is the name of a specific person, place, thing, or a title; for example:

• Natasha Trethewey, United States Poet Laureate as of 2012
• Carol Ann Duffy, Poet Laureate of the United Kingdom as of 2009
• Poets' Walk Park, Red Hook, NY
• Busboys and Poets (cafe), Washington, DC