Judith Madan (26 August 1702 – 7 December 1781) was an English poet. She was the grand daughter of Lady Sarah Cowper (1644–1720), the diarist.
She was the daughter of Spencer Cowper, Lawyer, Justice of the Common Pleas, and his wife Pennington, and is thought to have been born at the family seat, Hertingfordbury Park, Hertfordshire, England. As Judith Cowper she corresponded with Alexander Pope, whom she probably met. Cowper married Colonel Martin Madan, groom of the bedchamber to Frederick, Prince of Wales, and M.P. for Wootton Basset in 1723. He died at Bath on 4 March 1756, aged fifty-three. Their sons included Rev. Martin Madan, author of Thelyphthora a defence of polygamy, and the Right Rev. Spencer Madan, bishop successively of Bristol and Peterborough. Their elder daughter, Maria Frances Cecilia, married William Cowper of Hertingfordbury, her first cousin; the younger Penelope (died 22 December 1805), became the wife of General Sir Alexander Maitland (1728–1820). Judith was the aunt of William Cowper the English poet and hymnodist, and grandmother of General Frederick Maitland. She died at Stafford Row, Westminster on 7 December 1781.