The name Allyn is an English variant of the traditional name Allen, which is derived from the Old English given name Ællan or Alun. The name traces its origins to the Germanic tribes that settled in Britain during the 5th and 6th centuries AD. Ællan is believed to be a diminutive form of the Germanic name Alo, meaning "little rock" or "little hill."

One of the earliest recorded instances of the name Allyn can be found in the Domesday Book, a comprehensive survey of landholdings in England commissioned by William the Conqueror in 1086. The name appears as "Alluinus" or "Aluuinus," which were common spellings of the name during the Middle Ages.

In the 12th century, a prominent figure named Allyn de Lenn, also known as Alan of Lynn, was an English scholar and theologian who served as the Bishop of Thetford and later as the Abbot of Tewkesbury. He was known for his writings on the Cistercian order and his involvement in the ecclesiastical affairs of his time.

During the Renaissance period, an Italian humanist scholar named Allyn of Bruges, also known as Alanus de Insulis or Alan of Lille (c. 1128 - 1202), gained recognition for his philosophical and theological works, particularly his treatise on the nature of the soul, titled "De Planctu Naturae" or "The Complaint of Nature."

In the 19th century, Allyn Weston (1813 - 1849) was an American author and editor who published several works, including the novel "The Village Sketch Book" and a collection of essays titled "Hitherto: A Souvenir of the War." He was also involved in the abolitionist movement and worked as an editor for anti-slavery publications.

Another notable figure with the name Allyn was Allyn Capron (1854 - 1926), an American businessman and politician who served as the 53rd Governor of Rhode Island from 1923 to 1924. He was also involved in the textile industry and played a significant role in the economic development of his state.

While the name Allyn has been more commonly used as a surname in recent times, its historical origins can be traced back to the Old English and Germanic roots, with various spellings and variants appearing throughout different periods in history.