IN: Which person is he?
Todd was offered a recruitment letter from the Dean of Admissions himself because he had an athletic ability that was highly regarded by the university.
OUT: Todd

IN: Which person is it?
The bird perched on the limb and it sang.
OUT: The bird

IN: Which person is they?
McDonalds has many more restaurants than Chick Filet worldwide because they are a globally known.
OUT: McDonalds

IN: Which person is they?
Planet Express was bought out by Mom's Friendly Delivery Service so they can no longer be a threat.
OUT:
Planet Express