Marquess of Anglesey is a title in the Peerage of the United Kingdom. It was created in 1815 for Henry Paget, 2nd Earl of Uxbridge, a hero of the Battle of Waterloo, second in command to the Duke of Wellington. The Marquess holds the subsidiary titles of Earl of Uxbridge, in the County of Middlesex, in the Peerage of Great Britain (1784), Baron Paget, de Beaudesert, in the Peerage of England (1553), and is also an Irish Baronet, of Plas Newydd in the County of Anglesey and of Mount Bagenall in the County of Louth.

Henry William Paget, 1st Marquess of Anglesey, styled Lord Paget between 1784 and 1812 and known as the Earl of Uxbridge between 1812 and 1815, was a British Army officer and politician. After serving as a member of parliament for Carnarvon and then for Milborne Port, he took part in the Flanders Campaign and then commanded the cavalry for Sir John Moore's army in Spain during the Peninsular War; his cavalry showed distinct superiority over their French counterparts at the Battle of Sahagún and at the Battle of Benavente, where he defeated the elite chasseurs of the French Imperial Guard. During the Hundred Days he led the charge of the heavy cavalry against Comte d'Erlon's column at the Battle of Waterloo. At the end of the battle, he lost part of one leg to a cannonball. In later life he served twice as Master-General of the Ordnance and twice as Lord Lieutenant of Ireland.