Lismore (Irish: Lios Mór, meaning 'great ringfort')[2] is a historic town in County Waterford, in the province of Munster, Ireland.

As of the 21st century, Lismore supports a rural catchment area, and was designated as a "district service centre" in Waterford County Council's 2011–2017 development plan.

The imposing Lismore Castle, situated on the site of the old monastery since medieval times, lies on a steep hill overlooking the town and the Blackwater valley.

The castle remained in the possession of the Boyle family until it passed to the English Dukes of Devonshire in 1753 when the daughter of the 4th Earl of Cork, Lady Charlotte Boyle, married the Marquess of Hartington, who later succeeded as, in 1755, The 4th Duke of Devonshire, a future prime minister of Great Britain and First Lord of the Treasury.

Today, the castle continues in the private ownership of the Dukes of Devonshire who open the gardens and parts of the grounds for public access via a changing programme of local arts and education events.

[6] The medieval Lismore Cathedral, dedicated to St Carthage, variously damaged and repaired over the centuries, is notable for its architecture and the stained glass window by the English pre Raphaelite artist, Edward Burne-Jones.

A notable resident born in the town who has described her early life in Lismore, is the travel writer and world touring cyclist, Dervla Murphy.

[13] Lismore formerly had a rail station on the now dismantled Waterford to Mallow line and was served by the Cork to Rosslare boat train.