Yanar Dagh (Azerbaijani: Yanar Dağ, meaning "burning mountain") is a natural gas fire which blazes continuously on a hillside on the Absheron Peninsula on the Caspian Sea near Baku, the capital of Azerbaijan (a country which itself is known as "the Land of Fire"). Flames jet into the air 3 metres (9.8 ft) from a thin, porous sandstone layer. Administratively, Yanar Dagh belongs to Absheron District of Azerbaijan.

Unlike mud volcanoes, the Yanar Dagh flame burns fairly steadily, as it involves a steady seep of gas from the subsurface. It is claimed that the Yanar Dagh flame was only noted when accidentally lit by a shepherd in the 1950s. There is no seepage of mud or liquid, which distinguishes it from the nearby mud volcanoes of Lokbatan or Gobustan.

On the territory of Yanar Dagh, the State Historical-Cultural and Natural Reserve was established by the Presidential decree dated 2 May 2007 which operates under the control of State Tourism Agency of Azerbaijan. After major overhaul between 2017-2019, Yanar dagh Museum and Yanar dagh Cromlech Stone Exhibition were launched in the area of the Reserve.

In the first millennium BCE, the fire played a role in the Zoroastrian religion, as the link between humans and the supernatural spheres.