Yes, HERCULES is a Scrabble word!

Letter values in Scrabble US: H 4, E 1, R 1, C 3, U 1, L 1, E 1, S 1.

Is it a valid word?

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

(classical mythology) a hero noted for his strength; performed 12 immense labors to gain immortality
a large constellation in the northern hemisphere between Lyra and Corona Borealis

Not playable in Scrabble US: HERACLES, HERAKLES, ALCIDES.