Prince Regent (or Prince Regnant, as a direct borrowing from French language) is a prince who rules a country instead of a sovereign, e.g., due to the sovereign's incapacity (minority or illness) or absence (remoteness or non-existence).

Prince Regent in the UK

This title is normally associated with King George IV of the United Kingdom, who held it during the incapacity of his father, King George III (see Regent for other regents). Regent's Park and Regent Street in London are named after him.

This period is known as the English Regency, or just the Regency.