The name Blair is of Scottish Gaelic origin, derived from the Gaelic word "blar" meaning "field" or "plain." It is believed to have originated as a surname referring to someone who lived near a field or plain.

The earliest recorded use of the name Blair dates back to the 12th century, when it appeared as a surname in Scotland. One of the earliest recorded individuals with the name was William de Blair, who was mentioned in a charter from the reign of King William the Lion of Scotland (1165-1214).

In the Middle Ages, Blair was a common surname in Scotland, particularly in the counties of Ayr and Renfrew. It was also used as a place name, such as Blair Atholl and Blair Castle, which were associated with the influential Murray family.

The name Blair gained wider recognition during the Scottish Renaissance, when notable figures like Robert Blair (1593-1666), a Scottish Presbyterian minister and writer, and John Blair (1720-1800), a Scottish-American farmer and judge, rose to prominence.

As the name gained popularity, it began to be used as a given name as well. One of the earliest recorded instances of Blair as a first name was in the 18th century, when Blair Smith (1770-1857), an American politician and lawyer, was born.

Other notable individuals named Blair throughout history include:

1. Blair Underwood (born 1964), an American actor known for his roles in films and television shows like "L.A. Law" and "The New Adventures of Old Christine."

2. Blair Brown (born 1946), an American actress best known for her roles in films like "The Accidental Tourist" and "The Days and Nights of Molly Dodd."

3. Blair Rasmussen (born 1973), an Australian Olympic swimmer who won a gold medal in the 1992 Barcelona Olympics.

4. Blair Holcomb (born 1991), an American professional ice hockey player.

5. Blair Thornburgh (born 1983), an American author known for her young adult fiction novels.

While the name Blair has its roots in Scotland, it has gained worldwide recognition and is now used as a given name in various cultures and countries.