The name Dillan is derived from the Irish Gaelic name Dillón, which is a variant of the more common Irish name Dillon. The name Dillon itself is believed to have its origins in the Old Irish Gaelic word "dill" or "díl," meaning "pledge" or "tribute." It was a surname that emerged in medieval Ireland as a patronymic name, meaning "descendant of the pledge-giver."

In its earliest recorded use, the name Dillon was associated with the Dillon family, an ancient Irish clan that traced its roots back to the 6th century. The Dillon clan held significant power and influence in the province of Connacht, particularly in County Mayo and County Roscommon. The name Dillan, as a variant spelling of Dillon, likely emerged from this historical lineage.

One of the earliest recorded individuals with the name Dillon was Aedh Dillon, who lived in the 12th century and was a prominent member of the Dillon clan. He was known for his military exploits and his role in defending the clan's territories against rival clans.

Another notable figure bearing the name was Sir Robert Dillon, who lived in the 15th century and served as Chief Justice of the Irish Common Pleas. He played a significant role in the administration of justice during a turbulent period in Irish history.

In the 16th century, Sir Lucas Dillon, a member of the Dillon clan, gained recognition for his military service and his role in suppressing rebellions against English rule in Ireland. He was knighted for his loyalty to the English crown.

Moving forward to the 17th century, we find Theobald Dillon, a renowned Irish soldier and military leader who fought in the Wars of the Three Kingdoms. He was a staunch supporter of the Catholic cause and played a crucial role in the Irish Confederate Wars against English and Scottish forces.

In more recent times, one of the most famous individuals with the name Dillan was Dillan Merrill, an American singer-songwriter and musician who gained popularity in the early 2000s. Born in 1987, he achieved success with his unique blend of folk and indie rock music, releasing several critically acclaimed albums.

While the name Dillan has its origins in Ireland and has a long historical lineage, it has gained popularity across various cultures and regions in modern times, transcending its original Irish roots and becoming a name with global recognition.