Major-General Sir Thomas Aiskew Larcom, 1st Baronet PC FRS (24 December 1801 – 15 June 1879) was a leading official in the early Irish Ordnance Survey that started in 1824. He later became a poor law commissioner, census commissioner and finally executive head of the British administration in Ireland as under-secretary to the Lord-Lieutenant of Ireland, a position the government of the day was eager for him to take.
The longest-serving under-secretary (1853–1868), and a man of unusual abilities, Larcom had a distinguished career in his adopted country and acted with an impartiality that won him respect from all parties. In 1868 he was admitted to the Irish Privy Council and created a Baronet.