There were several Dukes of Lancaster in the 14th and early 15th Centuries. See also Duchy of Lancaster.

There were three creations of the Dukedom of Lancaster. The first Duke of Lancaster was Henry of Grosmont (c. 1306–1361), a great-grandson of Henry III; he was the 4th Earl of Lancaster before he was created the 1st Duke of Lancaster on March 6, 1351. His daughter Blanche married John of Gaunt, a son of King Edward III, and on November 13, 1362 John became the 1st Duke of Lancaster of the second creation. Upon John of Gaunt's death on February 4, 1399, the title passed to his son Henry Bolingbroke, Duke of Hereford, who became the 2nd Duke of Lancaster. Later that same year, Bolingbroke usurped the throne of England from King Richard II, ascending the throne as Henry IV. On November 10, 1399, the new king created his eldest son, Harry of Monmouth Duke of Lancaster. When Harry ascended the throne as Henry V in 1413, the title merged with the crown, with which it has remained ever since. The Duchy of Lancaster, however, continues to exist as a separate entity, one of only two Duchies in the United Kingdom.

Dukes of Lancaster, First Creation (1351)

• Henry of Grosmont, Duke of Lancaster (d. 1361)

Dukes of Lancaster, Second Creation (1362)

1. John of Gaunt, Duke of Lancaster (1350–1399)
2. Henry Bolingbroke, Duke of Lancaster (1367–1413) (became King in 1399)

Dukes of Lancaster, Third Creation (1399)

• Henry of Monmouth, Duke of Lancaster (1387–1422) (became King in 1413)