Lady Mary Dering (née Mary Harvey) (bap. 3 September 1629 – 7 February 1704) was an English composer. She was the daughter of Daniel Harvey of Combe, Croydon, Surrey, a turkey merchant in London (brother of Dr. William Harvey who first described blood circulation accurately) and his wife Elizabeth, daughter of Henry Kynnersley, also a London merchant.
At school in 1640, at Hackney's "ladies university of the female arts", she began a friendship with Katherine Philips (the Matchless Orinda). Mary studied with Henry Lawes, who dedicated his book to her; in the dedication he highly praises her compositions, and says that few of any sex have matched their perfection. Some of her music was published in John Playford's Select Ayres and Dialogues, and three of her songs were published in Lawes' Second book of airs; these are the first known published works by a woman in England.
On 5 April 1648 Mary Harvey was married to Sir Edward Dering. They had seventeen children, seven of whom died young. She survived her husband by twenty years, dying in February 1704 (1705 New Style); she also outlived her eldest son Sir Edward Dering, 3rd Baronet.
Lady Dering was buried at Pluckley in Kent, and has a memorial inscription in the church there.