The name Aileen has its origins in the Gaelic language, specifically in Ireland. It is derived from the old Irish name "Aoibhillinn," which means "little beautiful one" or "small and beauteous." The name is thought to have been in use since the Middle Ages, around the 12th or 13th century.

The name Aileen is a diminutive form of the Irish name Aoife, which itself means "beautiful" or "radiant." The spelling has evolved over time, with variations such as Aylina, Ailene, and Ailinn appearing in historical records.

One of the earliest recorded instances of the name Aileen can be found in the Annals of Ulster, a chronicle of medieval Irish history. In the year 1231, an entry mentions an "Aileen ingen Ruaidhri," which translates to "Aileen, daughter of Ruaidhri."

Throughout history, several notable individuals have borne the name Aileen. One of the most famous was Aileen Aroon, a 17th-century Irish noblewoman and muse of the Irish poet Sir Samuel Ferguson (1810-1886), who wrote a famous poem entitled "Aileen Aroon" in her honor.

Another notable Aileen was Aileen O'Beirne (1902-1974), an Irish sculptor and artist known for her religious statues and works depicting Irish mythology. Her sculptures can be found in churches and public spaces throughout Ireland.

In the literary world, Aileen Piper (1909-1997) was a renowned Australian author and poet, known for her works exploring the themes of love, nature, and the human experience. Her poetry collections include "The Half-Inhabited World" and "The Burning Cloud."

Aileen Wuornos (1956-2002) was an American serial killer, convicted of killing seven men in Florida between 1989 and 1990. Her life and trial were the subject of the 2003 biographical crime drama film "Monster," in which Charlize Theron portrayed Wuornos and won an Academy Award for Best Actress.

Finally, Aileen Quinn (born 1971) is an American actress best known for her role as Annie in the 1982 film adaptation of the musical "Annie." She had a successful career as a child actress and has continued to work in the entertainment industry as an adult.