Elizabeth Mortimer, Baroness Camoys (12 February 1371 – 20 April 1417) was an English noblewoman, the granddaughter of Lionel of Antwerp, 1st Duke of Clarence, and great-granddaughter of King Edward III. Her first husband was Sir Henry Percy, known to history as 'Hotspur'. She married secondly Thomas de Camoys, 1st Baron Camoys. She is represented as 'Kate, Lady Percy,' in Shakespeare's Henry IV, Part 1, and briefly again as 'Widow Percy' in Henry IV, Part 2.