The Gaels ( GAYLZ; Irish: Na Gaeil [n̪ˠə ˈɡeːlʲ]; Scottish Gaelic: Na Gàidheil [nə ˈkɛː.al]; Manx: Ny Gaeil [nə ˈɡeːl]) are an ethnolinguistic group native to Ireland, Scotland and the Isle of Man. They are associated with the Gaelic languages: a branch of the Celtic languages comprising Irish, Manx and Scottish Gaelic.

Gaelic language and culture originated in Ireland, extending to Dál Riata in western Scotland. In antiquity, the Gaels traded with the Roman Empire and also raided Roman Britain. In the Middle Ages, Gaelic culture became dominant throughout the rest of Scotland and the Isle of Man. There was also some Gaelic settlement in Wales, as well as cultural influence through Celtic Christianity. In the Viking Age, small numbers of Vikings raided and settled in Gaelic lands, becoming the Norse-Gaels. In the 9th century, Dál Riata and Pictland merged to form the Gaelic Kingdom of Alba. Meanwhile, Gaelic Ireland was made up of several kingdoms, with a High King often claiming lordship over them.

In the 12th century, Anglo-Normans conquered parts of Ireland, while parts of Scotland became Normanized. However, Gaelic culture remained strong throughout Ireland, the Scottish Highlands and Galloway. In the early 17th century, the last Gaelic kingdoms in Ireland fell under English control. James VI and I sought to subdue the Gaels and wipe out their culture; first in the Scottish Highlands via repressive laws such as the Statutes of Iona, and then in Ireland by colonizing Gaelic land with English-speaking Protestant settlers. In the following centuries Gaelic language was suppressed and mostly supplanted by English. However, it continues to be the main language in Ireland's Gaeltacht and Scotland's Outer Hebrides. The modern descendants of the Gaels have spread throughout the rest of the British Isles, the Americas and Australasia.

Traditional Gaelic society is organised into clans, each with its own territory and king (or chief), elected through tanistry. The Irish were previously pagans who had many gods, venerated the ancestors and believed in an Otherworld. Their four yearly festivals – Samhain, Imbolc, Beltane and Lughnasa – continued to be celebrated into modern times. The Gaels have a strong oral tradition, traditionally maintained by shanachies. Inscription in the ogham alphabet began in the 4th century. The Gaels' conversion to Christianity accompanied the introduction of writing in the Roman alphabet. Irish mythology and Brehon law were preserved and recorded by medieval Irish monasteries. Gaelic monasteries were renowned centres of learning and played a key role in developing Insular art; Gaelic missionaries and scholars were highly influential in western Europe. In the Middle Ages, most Gaels lived in roundhouses and ringforts. The Gaels had their own style of dress, which became the belted plaid and kilt. They also have distinctive music, dance, festivals, and sports. Gaelic culture continues to be a major component of Irish, Scottish and Manx culture.