Thomas Allnutt Brassey, 2nd Earl Brassey TD, DL, JP, MInstNA, AMICE (7 March 1863 – 12 November 1919), styled Viscount Hythe between 1911 and 1918, was a British peer, who was for many years editor or joint editor of Brassey's Naval Annual.
Brassey was the only son of Thomas Brassey, 1st Earl Brassey, by his first wife Anna, daughter of John Allnutt. He was educated at Eton and Balliol College, Oxford.
Brassey was an honorary Lieutenant in the London Brigade of Royal Naval Artillery Volunteers from 1888 to 1892. He acted as Assistant Private Secretary to Earl Spencer during the time the latter was First Lord of the Admiralty (1892–95), and in 1894 was Assistant Secretary of the Royal Commission on Opium that his father chaired.
He fought in the Second Boer War as Captain of 69 (Sussex) Company of the Imperial Yeomanry, and was acting Civil Commissioner for the British government at Pretoria following its surrender by the Boers in 1901.
He later joined the Queen's Own West Kent Yeomanry, becoming Lieutenant-Colonel in command in 1910, retiring in May 1914. He was awarded the TD in 1909. After the outbreak of the First World War he raised a second battalion to this regiment for home service, which he commanded until 1916, remaining on the Territorial Force Reserve. He was also attached to the Royal Engineers Transport Staff and his service entitled him to two campaign medals, but the location of the qualifying service is not given.