Denis O'Conor (1794 – 1847) of Clonalis, County Roscommon, was an Irish nobleman, the O'Conor Don and Member of Parliament (MP) in the British House of Commons.
He married, in 1824, Mary Anne, daughter of Major Blake, of Towerbill, County Mayo, and was the father of Charles Owen O'Conor and Denis Maurice O'Conor.
He was MP for Roscommon from 1831 to 1847. He became a Junior Lord of the Treasury in Lord John Russell's government but died the next year.