Lydney is a town and civil parish in Gloucestershire, England. It is on the west bank of the River Severn in the Forest of Dean District, and is 16 miles (25 km) southwest of Gloucester. The town has been bypassed by the A48 road since 1995. The population was about 8,960 in the 2001 census, reducing to 8,766 at the 2011 census. Increasing to 10,043 at the 2021 Census.

Lydney has a harbour on the Severn, created when the Lydney Canal was built. Adjoining the town, Lydney Park gardens have a Roman temple dedicated to Nodens.

According to Cook (1906) the toponym "Lydney" derives from the Old English *Lydan-eg, "Lludd's Island", which could connect it with the name Nudd/Nodens. However, alternative etymologies of Lydney are offered in other sources. A. D. Mills suggests "island or river-meadow of the sailor, or of a man named *Lida", citing the forms "Lideneg" from c. 853 and "Ledenei" from the 1086 Domesday Book.

Tourism:

• Norchard is the home of the Dean Forest Railway. It is a long heritage railway that runs between Lydney and Parkend in the Forest of Dean, Gloucestershire. The route was part of the former Severn and Wye Railway which ran from Lydney to Cinderford. The society that operates the line started steam locomotive operations in 1971, and bought the trackbed and line from British Rail in 1986, reaching Lydney Junction in 1995 and Parkend in 2005. Trains are operated by both steam and heritage diesel locomotives, and heritage diesel multiple units.
• Lydney Park is the site of a Romano-British Roman Temple and was an Iron Age hillfort. It also has gardens which are open to the public for a limited period each spring. In the late 4th century, the Romans built a Romano-Celtic temple to Nodens, a Celtic divinity who is reflected by the later figures of Nuada and Nudd/Lludd in Irish and Welsh mythology respectively. Lludd's name survives in the placename of Lydney. Several model dog images have been found there, indicating it was a healing shrine; dogs were associated with such shrines and may have been kept to lick wounds. The structure was a somewhat unusual design, rectangular rather than the usual square Romano-Celtic style temple. The end of the sanctuary or cella was not completely open, as usual; it had three rooms separated by stone walls. The walls of the cella were arched colonnades until a fault in the rock below caused the almost total collapse of the temple. It was rebuilt with solid walls. There was a fish-covered mosaic with an inscription that referred to 'Victorinus the Interpreter', probably an interpreter of dreams. The temple was accompanied by a large courtyard guest house, a long building used as dormitory accommodation and an elaborate bath suite or thermae.
• Taurus Crafts, which also occupies a section of the Lydney Park estate, is a Camphill community and popular visitor destination comprising a variety of craft shops and cafe.