The name Dylan is derived from the Welsh elements dy meaning "great" and llan meaning "enclosure" or "parish". It originated as a surname in Wales, referring to someone who lived in or came from a large parish or village.

The name can be traced back to the 6th century AD, when it first appeared as a surname in ancient Welsh genealogies and records. Some of the earliest recorded examples include Dillon map Naued, who lived in the 6th century, and Dyllon ap Cadwgan, who lived in the 12th century.

Dylan has been used as a given name since the late 18th century, likely inspired by the romantic image of Wales and its ancient Celtic heritage. One of the earliest recorded bearers of the name as a first name was Dylan Thomas, the renowned Welsh poet who was born in 1914 and died in 1953.

In literature, the name Dylan is associated with the legendary Welsh bard and mythical figure Taliesin, who is sometimes referred to as Dylan ail Don (Dylan the Son of the Wave) or Dylan ail Ton (Dylan the Son of the Surf). This connection likely contributed to the name's popularity and romantic associations.

Other notable individuals named Dylan throughout history include Dylan Marlais Thomas (1914-1953), a Welsh writer and poet; Dylan Aram (1949-1978), an American musician; Dylan Klebold (1981-1999), one of the perpetrators of the Columbine High School massacre; Dylan Moran (born 1971), an Irish comedian and actor; and Dylan McDermott (born 1961), an American actor.

The name Dylan has experienced a surge in popularity in recent decades, particularly in English-speaking countries. However, its roots can be traced back over 1,500 years to its origins as a Welsh surname, reflecting the rich cultural heritage and linguistic traditions of Wales.