John de Grey, 1st Baron Grey de Rotherfield, KG (29 October 1300^[1] – September 1359^[1]) was anEnglish soldier and courtier. John was the son and heir of Sir John de Grey, by Margaret who was daughter William de Odingsells and the granddaughter of Ida II Longespee.^[2]

John Grey of Rotherfield was one of the founder members of the Most Noble Order of the Garter. He is often confused with John Grey of Codnor, who bore the same coat of arms (Barry argent and azure).

By December 1349,^[1] John was Lord Steward of the Royal Household of King Edward III. He distinguished himself well in the Scotch and French wars. He was summoned to parliament many times from 1338 to 1357, and is thus regarded as having become Baron Grey of Rotherfield.^[1]

He married firstly, shortly before 1313,^[1] Katherine Fitzalan, daughter and coheir of Bryan FitzAlan, Lord FitzAlan of Bedale, Yorkshire. He married secondly Avice, daughter of John, 2nd Lord Marmion, a descendant of John of England.^{[3] [1]} by whom he had a son, Sir Robert de Grey.

He was succeeded by his son from his first marriage to Katherine Fitzalan, Sir John de Grey, 2nd Baron Grey de Rotherfield.