Lists of mountains in Ireland

In these lists of mountains in Ireland, those within Northern Ireland, or on the Republic of Ireland – United Kingdom border, are marked with an asterisk, while the rest are within the Republic of Ireland. Where mountains are ranked by height, the definition of the topographical prominence used to classify the mountain (e.g. the change in elevation required between neighbouring mountains), is noted. In British definitions, a height of 600 metres (1,969 ft) is required for a mountain, whereas in Ireland, a lower threshold of 500 metres (1,640 ft) is sometimes advocated.

The lowest minimum prominence threshold of any definition of an Irish mountain is 15 metres (49 ft) (e.g. the Vandeleur-Lynam), however most definitions, including the International Climbing and Mountaineering Federation (UIAA) criteria, do not consider prominences below 30 metres (98 ft) as being mountains (e.g. must at least be an Arderin or a Hewitt). Many British definitions consider a peak with a prominence below 150 metres (492 ft), as being a top, and not a mountain (e.g. must be a Marilyn). A widely used definition of an Irish mountain requires a minimum prominence of 100 metres (328 ft) (e.g. a HuMP), and is the basis for the 100 Highest Irish Mountains.

While Irish mountains are ranked according to Irish classifications, they are also ranked on classifications that cover Great Britain and Ireland (e.g. Simms and P600s).

There is no consensus on the definition of "mountain", but in Britain and Ireland it is often taken to be a summit over 2,000 ft, or more latterly, 600 m. There is less consensus about the topographical prominence requirement (e.g. the change in elevation required between neighbouring mountains), which can vary between 30–150 m (98–492 ft). Prominence is even strongly debated regarding UIAA classification of Himalayan mountains. In the alps, the UIAA requires a prominence of over 30 m to be a "peak" and over 300 m to be a "mountain".

The lowest threshold of prominence in Britain and Ireland is 15 metres (49 ft). The only definition in which prominence is not used, is where topographic isolation is used (e.g. the use of "sufficient separation" for Munros). Most Britain and Ireland definitions no longer categorise prominences below 30 metres (98 ft) (e.g. no new Nuttalls and Vandeleur-Lynams), and peaks with a prominence between 30–150 metres (98–492 ft) are now defined as tops rather than mountains (e.g. the 227 Munro Tops).

In Ireland, a prominence threshold of 100 metres (328 ft) is proposed for a mountain.

The term Dillon is used to describe any of the 212 Irish summits in Paddy Dillon's well–regarded Irish 2010 climbing guidebook: "The Mountains of Ireland". All of Dillon's summits are over 2,000 ft (610 m), and almost all have a prominence above 30 m (98 ft) (i.e. they are very similar to the list of 209 Irish Hewitts).

The term Myrddyn Deweys are peaks in Ireland, between 500 metres to 2,000 feet (609.6 metres) in height, with a prominence above 30 metres (98 feet), which was published by Michael Dewey and Myrddyn Phillips in 2000. Myrddyn Deweys are the Irish equivalent of Deweys, which extend the Hewitt classification down to 500 metres. There are 200 Myrddyn Deweys.