The name Eileen is derived from the Irish Gaelic name Eibhlín, which in turn is a diminutive form of the name Aoibheall. The name Aoibheall is composed of two elements: the first part "aoibh" means "pleasant" or "beautiful", while the second part "fhall" or "vall" means "beauty" or "dignity". Together, the full name Aoibheall can be translated to mean "beautiful maiden" or "beautiful princess".

The name Eileen emerged as an anglicized form of the Irish Eibhlín during the Middle Ages when many Irish names were adapted to English spelling and pronunciation. The earliest known written record of the name Eileen dates back to the 13th century in Ireland.

In Irish mythology, one of the most notable figures associated with the name Eileen is the character of Aoibheall, who was a beautiful princess and the daughter of the legendary Irish king Éochaid Iarlaith. She was renowned for her exceptional beauty and was pursued by many suitors.

One of the earliest recorded individuals with the name Eileen was Eileen O'Brien, an Irish noblewoman who lived in the 14th century. She was the wife of Rory O'Conor, the last High King of Ireland.

In the 16th century, Saint Eileen (or Eilien) was a Scottish Catholic martyr who was executed for her faith during the Scottish Reformation in 1594.

Another notable figure with the name Eileen was Eileen O'Connell (1838-1921), an Irish writer and activist who played a significant role in the Irish literary revival movement of the late 19th and early 20th centuries.

Eileen Gray (1878-1976) was a renowned Irish architect and furniture designer who is considered a pioneer of the modern movement in architecture and design.

Eileen Agar (1899-1991) was an influential British painter and collage artist who was a prominent figure in the Surrealist movement in the early 20th century.