Siyun
- Full/Birth Name:
- Yoon Siyun
- Korean Name:
- 윤시윤
- Group:
- AMPERS&ONE
- Position:
- Vocalist
- Birthday:
- Jan 8, 2005 (21 years old)
- Height:
- 180 cm (5ft 11in)
- MBTI:
- ISTJ
- Origin:
- South Korea
Siyun is a vocalist in AMPERS&ONE, born in Incheon, South Korea, and a former contestant on Treasure Box.