Brian (sometimes spelled Bryan in English) is a male given name of Irish and Breton origin, as well as a surname of Occitan origin. It is common in the English-speaking world.

It is possible that the name is derived from an Old Celtic word meaning "high" or "noble". For example, the element bre means "hill"; which could be transferred to mean "eminence" or "exalted one". The name is quite popular in Ireland, on account of Brian Boru, a 10th-century High King of Ireland. The name was also quite popular in East Anglia during the Middle Ages. This is because the name was introduced to England by Bretons following the Norman Conquest. Bretons also settled in Ireland along with the Normans in the 12th century, and 'their' name was mingled with the 'Irish' version. Also, in the north-west of England, the 'Irish' name was introduced by Scandinavian settlers from Ireland. Within the Gaelic speaking areas of Scotland, the name was at first only used by professional families of Irish origin.

It was the fourth most popular male name in England and Wales in 1934, but a sharp decline followed over the remainder of the 20th century and by 1994 it had fallen out of the top 100. It retained its popularity in the United States for longer; its most popular period there was from 1968 to 1979 when it consistently ranked between eighth and tenth. The name has become increasingly popular in South America, particularly Argentina and Uruguay, since the early 1990s.

The surname Brian is sometimes an English and Irish variant spelling of the surname Bryan. The English and French surname Brian is sometimes derived from the personal Celtic personal name shown above. The surname Brian can also sometimes be a French surname; derived from the Old Occitan word brian, meaning "maggot" and used as a nickname.

Variants of the name include Briant, Brien, Bran, Brion, Bryan, Bryant, Brjánn (in Icelandic) and Bryon. Variant spellings such as "Brien" are sometimes used as female given names, especially among members of the Irish diaspora.

In Latin America, the phonetic spelling “Brayan” is often used, associated with working-class parents aspiring to a higher socioeconomic status associated with Anglo-American culture, and mocked for that reason on social media.