| Lac-Nilgaut | |
| Flag Size: | 120x100px |
| Pushpin Map: | Canada Western Quebec |
| Pushpin Label Position: | top |
| Pushpin Map Caption: | Location in western Quebec |
| Coordinates: | 46.6°N -92°W |
| Subdivision Type: | Country |
| Subdivision Name: | Canada |
| Established Title1: | Constituted |
| Established Date1: | January 1, 1986 |
| Area Total Km2: | 9875.70 |
| Area Land Km2: | 8966.53 |
| Population Footnotes: | [1] |
| Population Total: | 5 |
| Population As Of: | 2021 |
| Population Density Km2: | 0.0 |
| Population Blank1 Title: | Pop (2016–21) |
| Population Blank1: | 0.0% |
| Population Blank2 Title: | Dwellings |
| Population Blank2: | 0 --> |
| Utc Offset: | −05:00 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | −04:00 |
| Postal Code: | J0X |
Lac-Nilgaut is a large unorganized territory in the Outaouais region, Quebec, Canada. With a surface area of 9851km2, it makes up over 70% of the northern portion of Pontiac Regional County Municipality.
The eponymous Lake Nilgaut is located roughly in the centre of the territory, at an altitude of over . This long lake is named after the nilgai (French: nilgaut|links=no), the largest Asian antelope and only found on the Indian subcontinent. The name was officially introduced in 1935, but it is unknown why this term was chosen to replace the original name Lac à l'Orignal (Moose Lake).[2]
Lake Nilgaut drains via the Nilgaut creek into the Noire River,[2] a major river that, together with the Coulonge River, bisects the territory.