Sisavang Vatthana (Lao: ????????????????????????????????????????????) or sometimes Savang Vatthana (full title: Samdach Brhat Chao Mavattaha Sri Vitha Lan Xang Hom Khao Phra Rajanachakra Lao Parama Sidha Khattiya Suriya Varman Brhat Maha Sri Savangsa Vadhana; 13 November 1907 – 13 May 1978 or 1984) was the last king of the Kingdom of Laos and the 6th Prime Minister of Laos serving from 15 October to 21 November 1951.
He ruled from 1959 after his father's death until his forced abdication in 1975.
His rule ended with the takeover by the Pathet Lao in 1975, after which he and his family were sent to a re-education camp by the new government.