1st Duke of Lancaster may refer to:

• John of Gaunt, 1st Duke of Lancaster, (1340 – 1399), member of the House of Plantagenet
• Henry of Grosmont, 1st Duke of Lancaster, (c. 1310 – 1361), also Earl of Derby, member of the English nobility

See also

• Duke of Lancaster

This disambiguation page lists articles associated with the title 1st Duke of Lancaster.
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