Amos Bad Heart Bull, also known as Waŋblí Wapȟáha (Eagle Bonnet) (ca. 1868-1913), was a noted Oglala Lakota artist in what is called Ledger Art. It is a style that adapts traditional Native American pictography to the new European medium of paper, and named for the accountants' ledger books, available from traders, used by the artists for their drawings and paintings. He was also the tribal historian of the Oglala, as his father Bad Heart Bull (Tȟatȟáŋka Čhaŋtéšiča) was before him.