The name Ellyn is a feminine given name of English origin, derived from the Old English name Ælwine. Ælwine is a compound name formed from the elements "ælf" (meaning "elf") and "wine" (meaning "friend"), suggesting a meaning of "elf friend" or "friend of the elves."

The name Ellyn gained popularity in the Middle Ages, particularly in England and parts of Scotland. It was sometimes spelled as Ellin, Elin, or Elyn during this period. The name has also been associated with the Hebrew name Ellen, which means "light" or "bright."

One of the earliest recorded instances of the name Ellyn can be found in the Domesday Book, a manuscript record of the great survey of England completed in 1086 AD on the orders of William the Conqueror. The name appears as "Ælwine" in this historical document.

In literature, the name Ellyn is mentioned in the epic poem "Sir Gawain and the Green Knight," written in the late 14th century. The character Lady Ellyn is described as a beautiful and virtuous woman.

Notable historical figures who bore the name Ellyn include:

1. Ellyn von Kruedener (c. 1583 – 1623), a German noblewoman and writer during the Renaissance period.
2. Ellyn Satterfield (c. 1590 – 1662), an English Puritan and one of the early settlers of the Massachusetts Bay Colony.
3. Ellyn Bache (1623 – 1700), an English Quaker and writer who advocated for women's rights and religious tolerance.
4. Ellyn Vaughan (1679 – 1751), a Welsh poet and translator who contributed to the preservation of Welsh literature.
5. Ellyn Goodrich (1905 – 1997), an American artist and illustrator known for her children's book illustrations.

While the name Ellyn has its roots in Old English and has been used throughout history, it remains a relatively uncommon name in modern times, though it continues to be used in various English-speaking countries.