Sir Littleton Ernest Groom KCMG KC (22 April 1867 – 6 November 1936) was an Australian politician. He held ministerial office under four prime ministers between 1905 and 1925, and subsequently served as Speaker of the House of Representatives from 1926 to 1929.

Groom was the son of William Henry Groom, who had arrived in Australia as a convict but became a prominent public figure in the Colony of Queensland. He was a lawyer by profession, entering federal parliament at the 1901 Darling Downs by-election following his father's death. Groom was first appointed to cabinet by Alfred Deakin in 1905. Over the following two decades he served as Minister for Home Affairs (1905–1906), Attorney-General (1906–1908), External Affairs (1909–1910), Trade and Customs (1913–1914), Vice-President of the Executive Council (1917–1918), Works and Railways (1918–1921), and Attorney-General (1921–1925).

A political liberal and anti-socialist, Groom was initially affiliated with Deakin's Protectionists, who were later superseded by the Liberals (1909) and Nationalists (1917). He came into conflict with Prime Minister Stanley Bruce during the 1920s, and as speaker in 1929 refused to use his casting vote to save the government on a confidence motion. He was expelled from the Nationalists and lost his seat at the resulting election, but was re-elected in 1931 as an independent. He joined the United Australia Party (UAP) in 1933 and continued as a backbencher until his death in 1936.