Sardar Baj Singh, also known as Baj Bahadur, was an eighteenth-century Sikh general, governor, scholar and martyr.
Sardar Baj Singh was the second of eight sons of Rao Nathiaji Puar. He was an umrah of Sarkar-e-Bangash on whose throne was his elder brother Sardar Bhagwant Singh Bangeshwar. Bhai Mani Singh was his cousin.
He led a cavalry of 2000 horsemen.
In the battle of Sirhind fought at Chappar Chiri in May 1710, Baj Singh was in command of the right wing of Banda Singh's army. He faced Nawab Wazir Khan in the battle striking his horse down with a lance. This led to the fall of Sarkar-e-Sirhind. Sardar Baj Singh became first governor of Khalsa Raj after this battle.
He was executed on 9 June 1716 on the outskirts of Delhi, on the bank of the Yamuna river along with his seven brothers and Banda Singh Bahadur.