Marquess of Normanby is a title that has been created twice, once in the Peerage of England and once in the Peerage of the United Kingdom.
The first creation came in 1694 in the Peerage of England in favour of John Sheffield, 3rd Earl of Mulgrave KG. He was a notable Tory politician of the late Stuart period, who served under Queen Anne as Lord Privy Seal and Lord President of the Council. In 1703 this first Marquess of Normanby was further honored when he was made Duke of Buckingham and Normanby. These titles became extinct on the death of the 2nd Duke in 1735.
The second creation came in the Peerage of the United Kingdom on 25 June 1838, in favor of Constantine Phipps, 2nd Earl of Mulgrave KG. He was a noted politician and served as Lord Lieutenant of Ireland and as Home Secretary. His great-grandfather William Phipps had married Lady Catherine Annesley, who was the daughter and heiress of James Annesley, 3rd Earl of Anglesey and his wife Lady Catherine Darnley (an illegitimate daughter of King James II by his mistress Catherine Sedley, Countess of Dorchester). Lady Catherine Darnley had later married John Sheffield, 1st Duke of Buckingham and Normanby, and hence Constantine Phipps, 2nd Earl of Mulgrave was the step-great-great-grandson of the 1st Duke of Buckingham and Normanby. Upon his death, Constantine Phipps, 1st Marquess of Normanby was succeeded by his son, the 2nd Marquess. He was a Liberal politician and also served as Governor of New Zealand. His grandson, the fourth Marquess, served briefly as a Lord-in-Waiting (government whip in the House of Lords) in 1945 and was also Lord Lieutenant of the North Riding of Yorkshire and of North Yorkshire. As of 2007 the titles are held by the latter's eldest son, the fifth Marquess, who succeeded in 1994.
The heir apparent is the present holder's son John Samuel Constantine Phipps, Earl of Mulgrave (b. 26 November 1994).