The River Clyde (Scottish Gaelic: Abhainn Chluaidh, pronounced [avɪɲˈxlˠ̪uəj]) is a major river in Scotland. It is the ninth longest river in the United Kingdom, and the third longest in Scotland. Flowing through the major city of Glasgow, it was an important river for shipbuilding and trade in the British Empire.

The Clyde is formed by the confluence of two streams, the Daer Water (the headwaters of which are dammed to form the Daer Reservoir) and the Potrail Water. The Southern Upland Way crosses both streams before they meet at Watermeetings (grid reference NS953131) to form the River Clyde proper. At this point the Clyde is only 10 kilometres (6 miles) from Tweed's Well, the source of the River Tweed, and 13 kilometres (8 miles) from the Devil's Beef Tub, the source of the River Annan.

From there it snakes northeastward before turning to the west, its flood plain used for many major roads in the area, until it reaches the town of Lanark. On the banks of the Clyde, the industrialists David Dale and Robert Owen, built their mills and the model settlement of New Lanark. The mills harness the power of the Falls of Clyde, the most spectacular of which is Cora Linn. A hydroelectric power station still generates electricity here, although the mills are now a museum and World Heritage Site.