Taeyang Choi (최태양), better known by his stage name Theo (테오) is a singer and the oldest member of the boy group P1Harmony, who debuted on October 28, 2020 under FNC Entertainment. Theo was born on July 1, 2001 in Daejon, South Korea. Prior to joining FNC Entertainment in 2018, he attended Daejon Dance and Vocal Academy, and later trained under SM Entertainment for 1 year. After training under FNC for 1 year and a half, Theo was revealed as the second member of P1Harmony on September 3, 2020. As of late 2023, P1Harmony has released 6 mini albums and 3 collaboration songs with other artists and producers.