The name Ronan is of Irish origin, derived from the Gaelic word "ronán," which means "little seal." It is believed to have emerged as a personal name in the early medieval period, around the 5th or 6th century AD, when it was common practice in Celtic cultures to name children after animals or natural elements.

One of the earliest recorded figures bearing the name Ronan was Saint Ronan, a 6th-century Irish abbot and missionary who established several monastic settlements in what is now Scotland. He is particularly revered in the Scottish Borders region, where the town of Innerleithen was formerly known as "Ronan's Toun" in his honor.

In ancient Irish literature, the name Ronan appears in the Ulster Cycle of heroic tales, which were likely composed between the 8th and 12th centuries. One notable character bearing the name is Ronan Fionn, a warrior and member of the Red Branch Knights who fought alongside the legendary figure Cú Chulainn.

Throughout the Middle Ages, the name Ronan remained relatively uncommon outside of Ireland and Scotland, but it continued to be used by Irish families, particularly those with ties to religious orders or monastic traditions. One notable bearer of the name was Ronan Finn (c. 1120-1189), an Irish cleric and writer who served as Archbishop of Armagh from 1176 until his death.

In more recent history, several individuals named Ronan have achieved prominence in various fields. These include Ronan O'Gara (born 1977), an Irish rugby union player who represented Ireland at the international level; Ronan Keating (born 1977), an Irish singer and musician who rose to fame as a member of the boy band Boyzone; and Ronan Farrow (born 1987), an American journalist and author known for his investigative reporting on the Harvey Weinstein scandal.

Other notable figures named Ronan include Ronan O'Rahilly (1940-2020), the Irish businessman and founder of the pirate radio station Radio Caroline; Ronan Bennett (born 1956), an Irish writer and screenwriter known for his novels and television work; and Ronan Vibert (born 1964), an English actor and voice artist best known for his work in animation and video games.