The Old Forest is a large woodland on the eastern border of Buckland located near the Shire, in the Middle-earth region of Eriador. . It is bordered in the east by the Barrowdowns and in the west by The Hay, a large hedge which the Hobbits of Buckland grew to protect their eastern border.

The Old Forest was one of the few remains of the vast primordial forests which covered most of Eriador before the Second Age, being its northern edge. What became known as the Old Forest was what survived the deforestation by the Númenóreans and the wars against Sauron. It was the part of Arnor during the existence of the North-kingdom. It was bordered in the east by the Barrow-downs, and in the west by Brandywine. Indeed, it had once been but the northern edge of one immense forest which reached all the way to Fangorn forest, hundreds of miles to the south-east.

The vicinity of the Old Forest was the domain of two nature-spirits: Tom Bombadil and Old Man Willow. The powers of these beings doubtless contributed to its survival when other forests were destroyed.[4] The house of Tom Bombadil was located beside the eastern eaves of the forest, near where the Withywindle stream flowed over a waterfall into the woods. Old Man Willow stood in the centre of the forest, on the Withywindle’s meandering banks.

The Old Forest was about 1,000 square miles in area. It was bordered on the east by the Barrow-downs, in the north it reached towards the Great East Road, and in the west and south it approached the Brandywine river. The Withywindle, a tributary of the Brandywine, ran through the heart of the forest, which covered most of the Withywindle’s drainage basin.

This was also a ‘catchment area’ in another sense. The landscape, trees and bushes were aligned so that if any strangers attempted to traverse the forest, then they were funnelled towards the Withywindle, and into the clutches of Old Man Willow in particular. The valley of the Withywindle within the Old Forest was known as the Dingle.

The Old Forest was a type of woodland nowadays described as temperate broadleaf and mixed forest. The west and south of the forest was dominated by “oaks and ashes and other strange trees”, which were generally replaced by pines and firs in the north. Beeches and alders were found here and there in the forest, and willows were dominant along the Withywindle.

Many of the trees were covered “with moss and slimy, shaggy growths.” The understorey was generally congested with bushes and other undergrowth, including brambles. A variety of plants grew in the forest’s occasional glades: grass, hemlocks, wood-parsley, fire-weed, nettles (Urtica dioica etc.) and thistles.

A variety of birds, mammals and insects were recorded in the vicinity of the Withywindle, but not elsewhere in the forest. Bombadil told tales of the “strange creatures of the Forest”,[14] but we are not provided with any elaboration.