The Withywindle is a river that runs through the Old Forest, from about Tom Bombadil's House until the Brandywine River. The ancient spirit named Goldberry, river-maiden and the wife of Tom Bombadil, is called the Daughter of Withywindle. Another entity, the Old Man Willow grew on the banks of the river, and through his malicious power the valley of the Withywindle was the most dangerous part of the Old Forest. Through his power over the trees, the Great Willow would draw unwary travellers to his domain on the banks of the Withywindle.
- A minor tributary of the River Baranduin or Brandywine. It rose above the house of Tom Bombadil and flowed approximately south-west to cut a valley through the trees of the Old Forest, before it met the Brandywine at Haysend near the southern edge of the forest.
- Meaning: "Willow-winding"
The name includes the old word withy, meaning 'willow'. The -windle element derives from wendel, which does not actually occur historically, but is used by Tolkien in various Old English river-names. The name of the river was apparently suggested by withywind, an old name for the tangling, climbing plant more commonly known as bindweed.
-  Marigold
- From its source in the mysterious Barrow-downs and all along its course through the Old Forest, the River Withywindle is a place of strange happenings and of dark and ancient legends. When adventuring in unknown areas within the Old Forest, travellers would be wise to avoid these winding, slow-moving waters, though doing so may prove difficult - The Withywindle has a way of drawing the unwary toward its deceptively tranquil surface and into its dark depths. It is also said that strange creatures of the forest - and even the very willow trees themselves along the Withywindle’s banks - are agents of its ancient evil. — Turbine