Emma Cust, Countess Brownlow, (28 July 1791 – 28 January 1872), formerly Lady Emma Sophia Edgcumbe, was the third wife of John Cust, 1st Earl Brownlow. The couple had no children, although the earl had children from his two previous marriages. Emma was born in Portugal Street (now Piccadilly), Hyde Park, London, the daughter of Richard Edgcumbe, 2nd Earl of Mount Edgcumbe, and his wife, the former Lady Sophia Hobart.