Sir John Grey (c. 1387 – 27 August 1439), English nobleman and soldier, of Ruthin, Denbighshire, Wales, Badmondisfield (in Wickhambrook), Suffolk, Great Gaddesden, Hertfordshire, etc., second but eldest surviving son and heir apparent of Sir Reginald Grey, 3rd Baron Grey de Ruthyn by his 1st wife, Margaret Roos.

He was Lord Lieutenant of Ireland in 1427-28, acting mainly through the Bishop of Meath as his Deputy.

[1] He married (first) before Trinity term 1410 (as her second husband) Constance Holland (c.1387–14 November 1437), the daughter of John Holland, 1st Duke of Exeter (half brother of King Richard II), by his wife, Elizabeth of Lancaster.

Sir Thomas Mowbray was executed on 8 June 1405 due to his revolt against her uncle, King Henry IV.

[1] Sir John Grey and Constance Holland had three children:[1] Constance, Countess Marshal, died 12 (or 14) Nov. 1437, and was buried in a chapel at St. Katherine by the Tower, London by her brother, John Holland, Duke of Exeter.