Yes, HUNTER is a Scrabble word!

Letter values in Scrabble US: H 4, U 1, N 1, T 1, E 1, R 1.

Is it a valid word?

HUNTER is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

someone who hunts game
a person who searches for something
a constellation on the equator to the east of Taurus; contains Betelgeuse and Rigel
a watch with a hinged metal lid to protect the crystal

Also: hunting watch.

Not playable in Scrabble US: ORION.