The name Allan has its origins in the Celtic language and was derived from the Gaelic word "aillin", which means "handsome" or "attractive". This name first appeared in Scotland and Ireland during the Middle Ages, around the 12th century.

Allan was a popular name among Scottish clans, particularly the Clan Allan. The earliest recorded instance of the name dates back to the 13th century, when a man named Allan Durward served as the High Constable of Scotland during the reign of King Alexander II.

In ancient texts, the name Allan is mentioned in the Irish legend of Fionn mac Cumhaill, where one of the members of Fionn's warrior band was named Allan. This legend dates back to the 3rd century AD and highlights the early use of the name in Celtic culture.

One of the most famous individuals with the name Allan was Allan Ramsay, a Scottish poet and playwright born in 1686. He is renowned for his contributions to the Scottish literary tradition and his portrayal of everyday life in his writings.

Another notable figure was Allan Pinkerton, an American detective born in 1819, who founded the Pinkerton National Detective Agency, one of the earliest private security firms in the United States.

In the field of science, Allan Dwan, born in 1885, was a pioneering American film director who worked in the early days of Hollywood and directed over 400 films throughout his career.

Allan Simonsen, born in 1978, was a Danish professional racing driver who competed in various prestigious motorsport events, including the 24 Hours of Le Mans.

Allan Holdsworth, born in 1946, was an influential English guitarist known for his innovative and unconventional playing style, which had a significant impact on jazz fusion and progressive rock music.