Baj Singh (d. 1716), a Bal Jatt, was a native of Mirpur Patti, a village in Amritsar district of the Punjab. A devoted Sikh, Baj Singh received the rites of initiation at the hands of Guru Gobind Singh himself. He accompanied the Guru to the Deccan in 1708 and was one of the five Sikhs sent by the dying Guru to the Punjab with Banda Singh Bahadur with the mission of putting an end to Mughal rule. He took part in all of Banda Singh's major campaigns.
For his fearlessness in battle, he came to be known as Baj Bahadur (Bahadur, lit. brave). 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. As the battle was won, Baj Singh was named administrator of the town. Baj Singh was captured at Gurdas Nangal in December 1715 and taken to Delhi where he was executed in June 1716 along with Banda Singh and his other companions.