Hannah Sarah O'Sullivan (born May 11, 1998) is an American amateur golfer.

She was raised in Chandler, Arizona, and attended Hamilton High School.

[3] Her win at the 2015 Gateway Classic makes her the youngest winner in the history of the Symetra Tour.

In May 2016, O'Sullivan became the top female golfer in the World Amateur Golf Ranking.

[6] She played college golf at Duke University.