Sir John Robert Mowbray, 1st Baronet PC (3 June 1815 – 22 April 1899), known as John Cornish until 1847, was a British Conservative politician and long-serving Member of Parliament, eventually serving as Father of the House.

Mowbray was the son of Robert Stirling Cornish and was educated at Westminster School and Christ Church, Oxford.

In 1847 he married Elizabeth Mowbray, the sole heiress of George Isaac Mowbray of Bishopwearmouth. The same year he assumed by royal licence the surname Mowbray in lieu of his patronymic to reflect the large fortune into which he married. They had three sons, all of whom succeeded to their father's baronetcy, and two daughters:^[1]

• Annie Maud Mowbray (died 29 Oct 1926), who married the Rev. Charles Thomas Cruttwell, canon residentiary of Peterborough
• Edith Marian Mowbray (died 27 March 1933), unmarried
• Sir Robert Gray Cornish Mowbray, 2nd Baronet (21 May 1850–23 July 1916)
• Sir Reginald Ambrose Mowbray, 3rd Baronet (5 April 1852–30 December 1916)
• Rev. Sir Edmund George Lionel Mowbray, 4th Baronet (26 June 1859–2 February 1919)

In 1853 Mowbray was elected to the House of Commons for Durham, a seat he held until 1868, and then represented Oxford University from 1868 until his death in 1899. In the House, he was chair of the Committee of Selection and of the Standing Orders Committee.^[2] He served as Judge Advocate General under the Earl of Derby from 1858 to 1859, and under Derby and later Benjamin Disraeli from 1866 to 1868. He was admitted to the Privy Council in 1858 and in 1880 he was created a baronet. From 1898 until his death the following year Mowbray was Father of the House of Commons.^[1]

A bronze bust was erected as a memorial in the House of Commons in 1900.^[2]