Is 300 Sparta real?

Yes, the 300 Spartans Were Real

If you refer to 'Spartans' as the full citizens of Sparta, which are accurately termed 'Spartiates', then indeed, there were 300 of them (in addition to King Leonidas) who were present at Thermopylae. Nevertheless, they represented only a segment of the advance contingent organized by a coalition of Greek city-states that had resolved to stand against the Persian forces.