Mount Leuser, Mountain summit in Aceh province, Indonesia.

Mount Leuser is the lowest of the three summits on the Leuser Range, a non-volcanic uplifted formation in Aceh, Sumatra, within Gunung Leuser National Park. Its western face drops precipitously toward the west coast, while the eastern approach rises through dense tropical rainforest. The summit stands at 3,119 metres with a prominence of 107 metres.

The area around Mount Leuser was first protected in the 1930s under Dutch colonial rule as a wildlife reserve. After Indonesian independence, it was gradually expanded into a national park, becoming one of the largest protected forest areas in Southeast Asia.

The names Loser and Leuser come from Gayo: los means "dead", and one account gives Leuser as "place where animals go to die". A colonial-era story tells of a Dutch officer who shot his hunting partner on Loser peak, and the porters' word los stuck to the range.

Bukit Lawang, a small village on the edge of the national park, is the most common starting point for treks in this area. A local guide is required for any entry into the park, and proper footwear and rain gear are essential given the wet forest conditions.

The name Leuser may come from a Gayo phrase meaning "place where animals go to die"; a folk story instead traces it to los, Gayo for "dead", after a Dutch officer accidentally shot his hunting partner on the range. Trekkers usually aim for Mount Loser, which is higher and easier to reach than Leuser.