Colcannon is a traditional Irish dish made primarily with mashed potatoes and cabbage or kale. The word "colcannon" is derived from the Irish Gaelic "cál ceannann," which means "white-headed cabbage." The earliest known references to the dish date back to the 18th century. It has been documented in Irish cookbooks since at least the early 19th century.

Colcannon typically includes ingredients such as potatoes, cabbage (or sometimes kale), butter, milk or cream, salt, and pepper. Some regional variations may add scallions, leeks, or chives. The potatoes are boiled and mashed with cooked and shredded cabbage or kale, and the mixture is enriched with butter and milk.

Colcannon was traditionally consumed during the autumn and winter, especially around Halloween. It was common for Irish families to serve colcannon as a substantial meal, sometimes with the addition of boiled ham or bacon. On Halloween (Samhain), small meaningful objects such as coins, rings, or thimbles were sometimes hidden in the colcannon, each symbolizing a different future for whoever found them.

The dish was affordable and filling, making it a staple among rural Irish households. Potatoes became widespread in Ireland in the late 16th century, and colcannon arose as a way to combine the staple crop with seasonal leafy vegetables.

Colcannon was referenced in Irish songs and poetry, such as the traditional song "Colcannon (The Skillet Pot)" which describes fond memories of eating the dish. It remains popular in Ireland today and is often served as a side dish, especially with boiled meats. The dish is also part of celebrations for St. Patrick’s Day and Halloween in Ireland and among the Irish diaspora.