What is the simple subject in the following sentence and why?

Nathaniel Hawthorne wrote ''Young Goodman Brown''.

Is it ''Nathaniel'' or ''Hawthorne''?

A simple subject does not mean one word. It means one idea. The simple subject is "Nathaniel Hawthorne".

The Nathaniel Hawthorne who went to my Dad's school and not the Nathaniel Hawthorne who went to my school wrote "Young Goodman Brown".

Here, the simple subject is "The Nathaniel Hawthorne who went to my Dad's school and not the Nathaniel Hawthorne who went to my school".

A compound subject is more than one idea/things.