The Liard River of the North American boreal forest flows through Yukon, British Columbia and the Northwest Territories, Canada.

Rising in the Saint Cyr Range of the Pelly Mountains in southeastern Yukon, it flows 1,115 km (693 mi) southeast through British Columbia, marking the northern end of the Rocky Mountains and then curving northeast back into Yukon and Northwest Territories, draining into the Mackenzie River at Fort Simpson, Northwest Territories.

The name comes from a particularly narrow spot near the river's headwaters, where Kaska people used to set goat snares.

Four days later, they reached the Frances River, and mistakenly ascended it, thinking it was the Liard's main branch.

Nine years later, another HBC employee, Robert Campbell, journeyed to the source of the Liard in the St. Cyr Range, renaming the river McLeod had ascended for Frances Ramsay Simpson, the wife of the Sir George Simpson, the HBC's governor who had authorised both expeditions.

This claim is contested by both the South Slavey Acho Dene Koe First Nation and Fort Nelson First Nation who count among their memberships the former residents of communities along the Liard along it's length in north-east BC east of the Rocky Mountains, like Nelson Forks, La Jolie Butte, and Francois, where the Acho Dene Koe signed Treaty 11.

A combination of factors led to their decline, the spread of sicknesses like the Spanish Flu said to be spread from river traffic travelling up the Liard River via the Northwest Territories hampered the indigenous population in the early 20th century as the fur trade continued to decline.

The discovery of oil and natural gas in the 1950s and the establishment of a local logging industry led to rapid migration of the local South Slavey indigenous population either north, to Fort Liard or south, to Fort Nelson.

The Liard River originates in south-eastern part of the Yukon, on the slopes of Mount Lewis, at 61°14′12″N 131°37′39″W / 61.23667°N 131.62750°W / 61.23667; -131.62750, at an elevation of 1,500 m (4,900 ft).

It then follows the southern rim of the St. Cyr Range of the Pelly Mountains, where the Ings River flows into it.