The name Meagan is an Anglicized form of the Irish name Muadhnait, which is derived from the Gaelic words "muad" meaning "honorable" and "nait" meaning "fire" or "radiant." The name was prominent in ancient Irish culture, dating back to the 5th century AD.

Meagan was originally a feminine name used by the Gaels, a group of Celtic peoples inhabiting Ireland and parts of Scotland. The earliest recorded instance of the name appears in the Annals of Ulster, an ancient chronicle of medieval Irish history, where it is spelled "Muadnait."

In the 9th century, the name Muadhnait was borne by an Irish princess who became a nun and was later canonized as Saint Muadhnait. Her feast day is celebrated on April 19th in the Catholic Church, and she is venerated as the patron saint of County Louth, Ireland.

Another notable figure with the name was Muadhnait Ní Cholmáin, a 12th-century Irish poet and princess from the kingdom of Uí Failghe. Her poems, which were written in the Irish language, were highly regarded during her lifetime and are still studied today.

As the name spread beyond Ireland, it underwent various spelling changes and adaptations. In the 16th century, the English variant "Meagan" emerged, and it grew in popularity during the 19th and 20th centuries.

One of the earliest recorded instances of the name "Meegan" (an alternative spelling) was in the 17th century. Meegan Bourke was an Irish noblewoman who lived from 1630 to 1689 and was known for her involvement in the Irish Confederate Wars.

In more recent history, Meagan Duhamel (1876-1964) was a Canadian author and educator who wrote extensively about the culture and history of the French-Canadian community. Meagan Lee Hagerty (1923-2011) was an American actress and singer who performed on Broadway and in films during the mid-20th century.