Lieutenant-Colonel Arthur John Bigge, 1st Baron Stamfordham, GCB, GCIE, GCVO, KCSI, KCMG, ISO, PC (18 June 1849 – 31 March 1931) was a British Army officer and courtier. He was Private Secretary to Queen Victoria during the last few years of her reign, and to George V during most of his reign. He was the maternal grandfather of Lord Adeane, Private Secretary to Elizabeth II from 1953 to 1972.
Bigge was the son of John Frederic Bigge (1814–1885) Vicar of Stamfordham, Northumberland and the grandson of Charles William Bigge (1773–1849) of Benton House, Little Benton, Newcastle on Tyne and Linden Hall, Longhorsley, Northumberland, High Sheriff of Northumberland and a prominent merchant and banker in Newcastle on Tyne. He was educated at Rossall School and the Royal Military Academy and was commissioned into the Royal Artillery in 1869.
Between 1878 and 1879, Bigge fought in the Anglo-Zulu War, as is known from his mentions in despatches. In 1880, he was warned to Balmoral Castle by Queen Victoria for giving an explanation on the Prince Imperial's death in the Zulu War. Before he was appointed as a Private Secretary, he had served as a groom-in-waiting and assistant private secretary to Queen Victoria. In 1881, he was appointed equerry-in-ordinary.
Bigge was appointed Private Secretary to Queen Victoria in 1895 and served until her death in January 1901. A couple of months later, he was appointed Private Secretary to her grandson, the Duke of Cornwall and York (appointed Prince of Wales later the same year). He continued to serve as such on the Prince´s accession to the throne as King George V in 1910, serving until his own death in 1931. As Private Secretary to the sovereign he was sworn of the Privy Council in 1910 and elevated to the peerage as Baron Stamfordham, of Stamfordham in the County of Northumberland, in 1911.
Bigge seemed to have an influence over King George and was one of those who supported the King's decision to adopt Windsor as the family name because of the keen anti-German feelings, which were arising during the World War I. On 17 July 1917 King George V "issued a proclamation declaring “The Name of Windsor is to be borne by His Royal House and Family and Relinquishing the Use of All German Titles and Dignities.”; persuading the King to deny asylum to Tsar Nicholas II and his family, who were thus forced to remain in Russia and who were murdered by the Bolsheviks; and interpreting the King's response "Bugger Bognor" as assent to the renaming of Bognor as Bognor Regis. He introduced the Duke of York (later King George VI) to Lionel Logue, who became the Duke's speech therapist. 
Bigge married Constance Neville (d. 1922) in 1881: they had a son and two daughters. Their son, Captain The Hon. John Neville Bigge (b. 1887), was killed in action near Festubert on 15 May 1915 whilst serving with the 1st Bn. King's Royal Rifle Corps. He is commemorated on Le Touret Memorial. A daughter, the Honourable Victoria Eugenie, married Captain Henry Robert Augustus Adeane. She was the mother of Michael Adeane, Baron Adeane, Private Secretary to Elizabeth II from 1953 to 1972.
- KCB : Knight Commander of the Most Honourable Order of the Bath (KCB) – 1895
- GCVO: Knight Grand Cross of the Royal Victorian Order (GCVO) – 2 February 1901 – on the day of the funeral of Queen Victoria
- KCMG: Knight Commander of the Order of St Michael and St George (KCMG) – 26 November 1901
- ISO: Imperial Service Order – 1903.
- KCSI: Knight Commander – 1906.
- PC : Privy Counsellor – 11 June 1910
- GCIE : Knight Grand Commander – 1911
- GCB : Knight Grand Cross – 1916.