Tiergarten (German: [ˈtiːɐ̯ˌɡaʁtn̩] ^ⓘ, literally Animal Garden, historically meaning deer park or hunting game park) is a locality within the borough of Mitte, in central Berlin (Germany). Notable for the great and homonymous urban park, before German reunification, it was a part of West Berlin. Until Berlin's 2001 administrative reform, Tiergarten was also the name of a borough (Bezirk), consisting of the current locality (Ortsteil) of Tiergarten (formerly called Tiergarten-Süd) plus Hansaviertel and Moabit. A new system of road and rail tunnels runs under the park towards Berlin's main station in nearby Moabit.

Once a hunting ground of the Electors of Brandenburg the Großer Tiergarten park of today was designed in the 1830s by landscape architect Peter Joseph Lenné. In the course of industrialization in the 19th century, a network of streets was laid out in the Hobrecht-Plan in an area that came to be known architecturally as the Wilhelmine Ring.

In 1894, the Reichstag building by architect Paul Wallot opened as the seat of the German parliament. The lawn between the contemporary Haus der Kulturen der Welt (House of World Cultures). The Reichstag building was the site of the Krolloper opera house, built in 1844, which served as the parliament house after the Reichstag fire on 27 February 1933. It was demolished by air raids in 1943.

On 15 January 1919 the socialist Karl Liebknecht was shot by Freikorps soldiers in the park near the lake Neuer See. The corpse of Rosa Luxemburg, murdered on the same day, was found in the nearby Landwehrkanal on 1 June 1919.

The first Institut für Sexualwissenschaft (Institute for Sex Research) of Magnus Hirschfeld was situated at the former In den Zelten street, near the contemporary Haus der Kulturen der Welt, from 1919 until it was closed by the Nazis in 1933.

A site next to the Tiergarten park is the former location of a villa at Tiergartenstrasse 4 where more than 60 Nazi bureaucrats and doctors worked in secret under the "T4" program to organize the mass murder of sanatorium and psychiatric hospital patients deemed unworthy to live. The German national memorial to the people with disabilities systematically murdered by the Nazis was dedicated in 2014 in Berlin at that site. Although the villa was destroyed, a Stolperstein set in the pavement on Tiergartenstraße marks its location and historic significance.

After 1944, the park was largely deforested because it served as a source of firewood for the devastated city. In 1945, the Soviet Union built a war memorial along the Straße des 17. Juni, the Tiergarten's main east–west artery, near the Brandenburg Gate. The Tiergarten itself became part of the British sector.

The Tiergarten houses many parliamentary and governmental institutions, among others the Bundestag in the Reichstag building and the new German Chancellery. The residence of the German President, Schloss Bellevue and the Carillon are located in the Tiergarten park. It contains several notable sculptures, including the four-tiered Victory Column (Siegessäule), the Bismarck Memorial and several other memorials to prominent Prussian generals, all of which were located in the ceremonial park facing the Reichstag, before they were moved to their present location by the Nazis. The tree-lined pedestrian avenues emanating from the Victory Column contain several ceremonial sculptures of Prussian aristocrats enacting an 18th-century hunt.