List of dukedoms in the peerages of Britain and Ireland

This article lists all dukedoms, extant, extinct, dormant, abeyant, or forfeit, in the peerages of England, Scotland, Great Britain, Ireland and the United Kingdom.

By the end of the Middle Ages, traditionally marked by the Battle of Bosworth Field on 22 August 1485, a total of 31 dukedoms (with 16 distinct titles) had been created; yet only those of Cornwall, Lancaster and Suffolk remained.

Elizabeth did not create any dukes, and she beheaded Thomas Howard at the age of 36 for plotting to wed Mary, Queen of Scots and overthrow her.

As a result, the rules of succession to a ducal title are usually explicitly laid out in the patent, and are not necessarily consistent, nor do they coincide with common inheritance laws on property.

For instance, an heir does not usually inherit the ducal title by virtue of being the heir of the last holder, but by virtue of descent from the first person to whom the title was given, so a full-blood daughter of a duke may be superseded by a half-blood male relative who can prove direct descent from the first holder.