A third suspect was arrested in an alleged “anti-white” crime that left a 57-year-old grandmother bloodied with a head injury after she was attacked on a Queens bus last month, police said.

With two teenage girls already nabbed, Jahnaiya Williams, 19, of Queens, was taken into custody Monday morning, the NYPD said. She is charged with assault and aggravated harassment. Both are classified as hate crimes, authorities said.

Three assailants approached victim Jill LeCroix, a grandmother of five, and struck her in the head with an unknown object while making anti-white statements in the July 9 attack, police have said. The victim required three staples on her head.

The other two suspects, 15 and 16, were not named when they were arrested late last month due to their age. But they also face assault and aggravated harassment charges classified as hate crimes in connection to the incident on the southbound MTA bus near Jamaica Avenue and Woodhaven Boulevard, police said.

LeCroix told The Post days after the attack that three suspects accused her of being a supporter of former President Donald Trump, and one of the attackers told her “she hates white people, the way they talk, hates white skin, the way their skin cracks.”

“Never in my life have I been attacked like that,” said LeCroix.