Patuan Bosar Sinambela ginoar Ompu Pulo Batu, better known as Si Singamangaraja XII, was the last priest-king of the Batak peoples of north Sumatra. In the course of fighting a lengthy guerrilla war against the Dutch colonisation of Sumatra from 1878 onwards, he was killed in a skirmish with Dutch troops in 1907. He was declared a National Hero of Indonesia in 1961 for his resistance to Dutch colonialism.

Batak is a collective term used to identify a number of closely related Austronesian ethnic groups predominantly found in North Sumatra, Indonesia, who speak Batak languages. The term is used to include the Karo, Pakpak, Simalungun, Toba, Angkola, and Mandailing, related ethnic groups with distinct languages and traditional customs (adat).