Neil is an English, Irish, and Scottish masculine given name, ultimately derived from the Irish name Niall. The origin of Niall is debated: it may stem from the Old Celtic root nītu- meaning "fury, passion" or be related to the Old Irish word nia ("hero"). Another possible source is Old Irish nél ("cloud"). Etymology and Historical Development The name Niall was borne by several early Irish kings, including the semi-legendary Niall of the Nine Hostages, a high king of the 4th or 5th century. Niall's dynasty, the Uí Néill, dominated Ireland for centuries and the name's popularity grew through their influence. During the early Middle Ages, Norse raiders and settlers in Ireland encountered the name and adapted it as Njáll in Old Norse, Njål in Norwegian. The Vikings carried the name to Iceland, then to Norway, Denmark, Normandy, and eventually to England, while Irish migration introduced it to Northern England and Scotland independently. The Normans, of Scandinavian origin, also used Neil, and the Middle English form Nigel (from Old French Néel) emerged as a related variant. Spread and Modern Usage Though Neil was common in Ireland and Scotland throughout the Middle Ages, it did not become widespread in England and North America until the 20th century, gaining steady popularity across the English-speaking world. The name is sometimes Anglicized as Neal, and also gave rise to surnames such as Neil, Nelson 1, Nielson, and Niles. The most famous bearer in modern times is American astronaut Neil Armstrong (1930–2012), the first person to walk on the moon, whose prominence cemented the name's international recognition. The Scottish feminine form is Neilina. Meaning: Debated – possibly "fury, passion" (Celtic nītu-) or "hero" (Old Irish nia); also suggested: "cloud" (Old Irish nél). Origin: Irish (via Niall), with Norse and Norman transmission. Type: First name. Usage Regions: English, Irish, Scottish (and broadly English-speaking world).