Hannah Parkhouse was the daughter of Hannah and Philip Parkhouse, a bookseller. Details about her early life are scarce. She had some classical education. Between 1768 and 1772, she married Thomas Cowley, who worked in the Stamp Office and was a part-time journalist and theater critic, and moved with him to London. One night, Hannah Cowley and her husband went to the theater to see The School for Wives. She thought she could write a play herself, and finished one in less than three weeks. Her first published work was The Runaway (1776), produced at the Theatre Royal, Drury Lane by actor-manager David Garrick and starring Sarah Siddons. Hannah Cowley went on to become the most successful female playwright of late 18th-century England. Her most popular play was The Belle’s Stratagem (1782), a comedy of manners that was frequently produced for the professional stage and in amateur theatricals. The most notable production was by Henry Irving in 1881 and starred Ellen Terry in the lead role. Over the course of her career, Hannah Cowley wrote a total of 13 plays. She originally drew heavily from Restoration comedy and adapted works by Aphra Behn, Susanna Centlivre, and Molière, but later experimented with a wide range of genres. Her work was well known to other writers of the period such as Jane Austen. In 1783, Thomas Cowley took a job with the British East India Company and moved to India, never to return, leaving Hannah to raise their children. She wrote plays until 1794, and then retired to Tiverton, where she composed long narrative poems under the pseudonym "Anna Matilda" and presided over a salon for women.