The name Caitlyn is a modern variation of the traditional Irish name Caitlín, which is the Irish Gaelic form of the name Cathleen or Kathleen. The name Cathleen itself derives from the ancient Greek name Katharina, which means "pure" or "clear."

The earliest known record of the name Caitlín dates back to the 17th century in Ireland. It was a common name among Irish families, particularly in the rural areas of the country. The name gained popularity in the 19th and early 20th centuries, with many Irish immigrants bringing the name to other parts of the world, such as the United States and Canada.

While the name Caitlyn is not found in ancient texts or religious scriptures, its root name, Katharina, has a rich history. In the 4th century, there was a Christian saint named Saint Catherine of Alexandria, who was martyred for her faith. This association with a revered saint likely contributed to the widespread popularity of the name Katharina and its various forms across Europe.

One of the earliest recorded individuals with the name Caitlyn was Caitlyn Jenner, the American television personality and former Olympic gold medalist in decathlon, born in 1949. Jenner gained widespread attention in 2015 when she publicly announced her transition and adopted the name Caitlyn.

Another notable figure with the name Caitlyn is Caitlyn Vermylen, a Canadian singer-songwriter born in 1986. She has released several albums and received nominations for various music awards.

In the literary world, Caitlyn R. Kiernan is an American writer known for her gothic fiction and comic book work, born in 1964. Her novels and short stories have been acclaimed and honored with numerous awards.

Caitlyn Jenner, the American reality television star and former athlete, born in 1949, is one of the most well-known individuals with the name Caitlyn in recent times.

Caitlyn Cary is an American singer and songwriter, born in 1988, known for her work in the country and Americana genres. She has released several albums and received critical acclaim for her songwriting.

These are just a few examples of individuals throughout history who have borne the name Caitlyn, showcasing its Irish roots and modern popularity.