Rev. William Betham (1749–1839) was an English clergyman and antiquarian, best known for his work on the history of the English Baronetage.
He was born at Little Strickland, near Morland, Westmoreland, on 17 May 1749. His father was William Betham, born in 1698. He was educated at the public school of Bampton, was ordained in 1773, apparently without graduating at a university, and became chaplain to the Earl of Ancaster. From 1784 to 1833 he was head master of the endowed school at Stonham Aspel in Suffolk, which post he resigned in 1833, on being presented to the rectory of Stoke Lacy, in the Diocese of Hereford. He died six years later in 1839, aged 90.
In 1774, he married Mary Damont, daughter of William Damont, of Eye, Suffolk. They had fifteen children. Sir William II Betham, born in 1779, was his eldest surviving son who became an antiquarian and herald. He was Ulster King of Arms from 1820 until his death in 1853. Their daughter Mary Matilda Betham was a painter and a poet.