Kim Jun Seo is a South Korean singer, dancer, actor, former member of 1THE9 (원더나인), and current member of WEi (위아이) and ALPHA DRIVE ONE (알파드라이브원; also stylized as ALD1 (알디원)). He dropped out of Mugeo High School before passing the High School Graduation Certification Examination.

In 2018, he appeared in the singing survival show "UNDER19" and finished in 9th place, thus earning a spot in the resulting project group. He made his debut in April 2019 as 1THE9's lead vocalist, lead dancer, rapper and visual with their first mini-album, "XIX". They were supposed to be active for around one year, so in August 2020, PocketDol Studio (포켓돌스튜디오) announced their disbandment.

He returned to his previous agency, OUI Entertainment (위엔터테인먼트), and re-debuted in October 2020 as WEi's lead dancer, sub-vocalist and maknae with their first EP "Identity: First Sight".

He made his acting debut in 2025 with the lead role in the BL web drama "Secret Relationships". In May of that year, he went on hiatus from all WEi activities as he entered the reality competition "Boys II Planet". He finished in 8th place and secured a spot in the resulting project group. They released the pre-debut single, "Formula", in December 2025. He officially re-debuted as part of ALPHA DRIVE ONE in January 2026 with their first mini-album, "Euphoria". The group is managed by Wakeone (웨이크원) and the initial contract is for 5 years.

(Source: kisskh) Edit Biography