Niels Thomasius Neergaard (27 June 1854 – 2 September 1936) was a Danish historian and political figure, a member of the Liberal Moderate Venstre and since 1910 of Venstre. He served as Council President of Denmark between 1908 and 1909 as head of the Cabinet of Neergaard I and as both Prime minister of Denmark and Finance Minister from 5 May 1920 to 23 April 1924, leading the Cabinet of Neergaard II and III. His last cabinet office was as Finance Minister (14 December 1926 – 30 April 1929).
Neergaard's greatest challenges as a politician were as Prime Minister and Finance Minister after the Easter Crisis of 1920, organizing the return of South Jutland to Danish rule and having to deal with the economic crisis brought on by World War I. He also had a significant influence on the content of the Constitution of 1915.
Neergaard's largest work as a historian, Under junigrundloven (1892-1916), is still considered the primary work on Danish politics 1848-66.