Sir James Penn Boucaut, KCMG, (29 October 1831 – 1 February 1916) was a South Australian politician and judge. He was a member of the South Australian House of Assembly on four occasions: from 1861 to 1862 for City of Adelaide, from 1865 to 1870 for West Adelaide (1865–1868) and The Burra (1868–1870), from 1871 to 1878 for West Torrens (1871–1875) and Encounter Bay (1875–1878), and a final stint in Encounter Bay in 1878.
Boucaut was Premier of South Australia three times: from 1866 to 1867, from 1875 to 1876, and from 1877 to 1878. He was Attorney-General of South Australia under Premiers John Hart and Henry Ayers, and served variously as Attorney-General, Treasurer, Commissioner of Public Works and Commissioner of Crown Lands and Immigration in his own ministries. He left politics in 1878 when he was appointed a judge of the Supreme Court of South Australia, serving until his retirement in 1905.
Boucaut was born in Mylor, Cornwall, the eldest son of a navy officer, Captain Ray Boucaut, and his wife, Winifred, daughter of James Penn, superintendent of the royal dockyard at Falmouth. He was educated at the Rev. Mr Hayley's school at Saltash.
Boucaut left with his parents for South Australia in 1846, and after some work as a in the interior, returned to Adelaide and entered the legal profession. Boucaut was articled to Charles Fenn, and was admitted to the bar in November 1855, his career was a lawyer was successful. In December 1861 he was returned to the South Australian House of Assembly as a representative for the City of Adelaide district, but was defeated at the general election in 1862. In March 1865 he was elected for West Adelaide at the head of the poll. In October he became Attorney-General in the first Hart ministry, and when the premier retired to go to England in February 1866, Boucaut took his place in a reconstructed ministry which was in power until May 1867. Boucaut was narrowly defeated in the 1868 election for East Adelaide, but a few days later on 15 April he was returned unopposed for the The Burra, where his father-in-law, Alexander McCulloch, stood down in his favour. He badly lost the 1869 election for The Burra but entered the house again as member for West Torrens in the by-election of 1871. In January 1872 he became Attorney-General in Ayers' sixth ministry, but retired when the cabinet was reconstructed early in March.