The given name Shea is believed to have originated from the Irish Gaelic word "Sídhe," which refers to the mythological fairy-folk or fairies in Irish folklore. It is thought to have been derived from the Old Irish word "síd," meaning "mound" or "hill," as the fairies were believed to reside in these natural formations.

In Irish mythology, the Sídhe were a race of supernatural beings who lived in the otherworld, often described as underground fairy mounds or ancient burial sites. They were revered and sometimes feared by the Celtic people of Ireland, who believed they possessed magical powers and could influence the lives of mortals.

The earliest recorded use of the name Shea dates back to the 12th century, where it appeared in Irish annals and historical records. One of the earliest documented individuals with this name was Shea O'Donnell, a 12th-century Irish chieftain and King of Tyrconnell, a region in what is now County Donegal, Ireland.

Throughout the centuries, the name Shea has been borne by several notable figures in Irish history. One such individual was Shea O'Neill, also known as Shane O'Neill (c. 1530-1567), an Irish chieftain and leader of the O'Neill clan who led a rebellion against English rule in Ireland during the 16th century.

Another prominent figure with this name was Shea O'Hara (c. 1550-1617), an Irish poet and soldier who served under Hugh O'Neill, the Earl of Tyrone, during the Nine Years' War against English forces in Ireland.

In the 18th century, Shea was the first name of Shea Kearney (c. 1720-1786), an Irish harper and composer who is credited with preserving and transmitting many traditional Irish airs and tunes.

Moving into the 19th century, Shea Sargent (1811-1863) was an Irish-American writer, newspaper editor, and politician who served as the 15th Mayor of San Francisco, California, from 1856 to 1857.

While the name Shea has its roots in Irish culture and mythology, it has also been adopted and used in other parts of the world, particularly in English-speaking countries with Irish diaspora communities. It remains a popular given name, particularly in Ireland and among those of Irish descent.