Seo Ju-hyun (Hangul: 서주현; born June 28, 1991), known professionally as Seohyun (Hangul: 서현), is a South Korean singer-songwriter and actress. She debuted as a member of SM Entertainment girl group Girls' Generation (and later its subgroup Girls' Generation-TTS) in August 2007. She debuted as a solo artist with the release of her mini album titled Don't Say No, for which she penned the lyrics of all the songs except the title track, "Don't Say No".