First Name: Sung Yoon
Family Name: Choi
Native name: 최성윤
Also Known as: Sungyoon;최성윤
Nationality: South Korean
Gender: Male
Born: July 31, 1995

Choi Sung Yoon, also known by his stage name Y, is a South Korean singer and actor. He is the main vocalist of the boy band Golden Child under Woollim Entertainment.
He made his debut as an actor in 2014 with the drama My Lovely Girl alongside fellow member Lee Dae Yeol.