Vien is a surname of French origin, as well as another spelling of the Vietnamese given name Viên (which often finds use alone following a title and thus appearing to English speakers to be a surname).
Those bearing the surname include:
Joseph-Marie Vien (1716–1809), French painter Thomas Vien (1881–1972), Canadian politician Jacques Vien (1932–2017), Canadian politician Dominique Vien (born 1967), Canadian politician
Those bearing the given name include:
Cao Văn Viên (1921–2008), South Vietnamese General Linh Quang Viên (1918–2013), South Vietnamese Lieutenant General Nguyễn Thị Ánh Viên (born 1996), Vietnamese swimmer