Patuan Bosar Sinambela ginoar Ompu Pulo Batu, better known as Si Singamangaraja XII (1849 – 17 June 1907), was the last priest-king of the Batak peoples of north Sumatra.

He was not normally seen as a political figure, but when Dutch colonists and missionaries began penetrating north Sumatra from the 1850s onwards both Sisingamangaraja XI and XII became the focus of Batak resistance to colonial rule.

Although they were not personally anti-Christian, the two Sisingamangarajas faced pressure to act from traditional list Batak chiefs and the neighbouring Sultanate of Aceh, which was at war with the Dutch from 1873.

[8] The Dutch mounted a harsh response, torturing and killing Bataks suspected of being followers of Sisingamangaraja XII, as well as burning houses and imposing punitive taxes.

[9] In 1904, Dutch forces under Lt Col Gotfried Coenraad Ernst van Daalen attacked Tanah Gayo and some areas around Lake Toba in order to break the Batak resistance.