简·格雷（Lady Jane Grey，1537年10月12日－1554年2月12日）是一位英格兰女王。她在位仅仅数日，而且她的女王地位也有争论（在位只有九天，一般不正式算作英国女王）。她的继位违反了英国的议会法令，在这一点上虽然她在英国历史上并非独一无二的，但后来她的王位也被否认了。就连她登基的日期在历史上也是有争议的；有人认为她是1553年7月6日，英王爱德华六世逝世当日，成为女王的，按这个说法她也被称为“十三日女王”，但根据英国皇室官方网页上显示，她是在7月10日正式成为女王的，在这一天她的继位被公布。按这种说法她是一位“九日女王”。她于7月19日被废黜。

Lady Jane Grey (1536/1537 – 12 February 1554(1554-02-12)), also known as Lady Jane Dudley or the Nine-Day Queen, was an English noblewoman and de facto monarch of England from 10 July until 19 July 1553.

The great-granddaughter of Henry VII through his younger daughter Mary, Jane was a first cousin once removed of Edward VI. In May 1553, she was married to Lord Guildford Dudley, a younger son of Edward's chief minister, John Dudley, Duke of Northumberland. When the 15-year-old king lay dying in June 1553, he nominated Jane as successor to the Crown in his will, thus subverting the claims of his half-sisters Mary and Elizabeth under the Third Succession Act. Jane was imprisoned in the Tower of London when the Privy Council decided to change sides and proclaim Mary as queen on 19 July 1553. Jane was convicted of high treason in November 1553, which carried a sentence of death, although her life was initially spared. Wyatt's rebellion of January and February 1554 against Queen Mary I's plans to marry Philip of Spain led to the execution of both Jane and her husband.