- Name: Yohan Ok (옥요한)
- Stage name: Yohan (요한)
- Fan names: Yoth, Yoddoong (요뚱)
- Birth place: Busan, South Korea
- Birth date: December 27, 1975
- Part: Vocal, lyrics, composition
- Association: PIA
- Yohan is a very outspoken proponent for the advancement of Korean rock music.
- He is able to play the guitar and drums.
- Yohan writes a large amount of PIA's music (along with SimZ) in addition to all of its lyrics.
- He (along with the other members of PIA) is an avid soccer fan - PIA has performed twice for FIFA World Cup in Korea, first in 2006 and again in 2010.
- He currently resides in Seoul, South Korea.
- He once stated in an interview that when he retires from music, he'd like to be a florist in a flower shop.