Elizabeth Hay, Countess of Erroll

Elizabeth Hay, Countess of Erroll (17 January 1801 – 16 January 1856; born Elizabeth FitzClarence) was an illegitimate daughter of King William IV of the United Kingdom and Dorothea Jordan. She married William Hay, 18th Earl of Erroll, and became Countess of Erroll on 4 December 1820 at age 19. Due to Hay's parentage, William Hay became Lord Steward of the Household. Elizabeth and William Hay married at St George's, Hanover Square. Hay is pictured in a FitzClarence family portrait in House of Dun and kept a stone thrown at her father William IV and the gloves he wore on opening his first Parliament as mementos. She died in Edinburgh, Scotland.

Elizabeth and William Hay together had four children.

British Prime Minister David Cameron is a fourth great grandson of Elizabeth Hay, thus making him the fifth cousin, twice removed to Queen Elizabeth II according to Debrett's.