The name Gannon has its origins in the Gaelic language and can be traced back to ancient Ireland. It is derived from the Irish word "gann" which means "fair" or "lean." The name is thought to have been initially used as a descriptive term for someone with a slender or fair appearance.

One of the earliest recorded instances of the name Gannon can be found in the Annals of the Four Masters, a chronicle of medieval Irish history compiled in the early 17th century. The text mentions a figure named Gannon mac Scandail, who lived in the 6th century and was a member of the Uí Bairrche clan in County Carlow.

In the 9th century, a renowned Irish scholar and philosopher named Gannon of Bangor lived and taught at the monastic school of Bangor Abbey in County Down. He was highly respected for his wisdom and contributed significantly to the intellectual and spiritual life of early medieval Ireland.

During the Norman invasion of Ireland in the 12th century, a notable figure named Gannon O'Rourke fought against the Norman forces. He was a member of the ruling O'Rourke dynasty in the Kingdom of Breifne, which covered parts of modern-day counties Leitrim and Cavan.

In the 16th century, a Franciscan friar named Gannon Nagle gained recognition for his work in establishing schools and promoting education in Ireland. He was born in County Cork around 1570 and played a significant role in preserving Irish culture and learning during a period of English colonial rule.

Another historical figure with the name Gannon was an Irish patriot and rebel leader from the late 18th century named Gannon Ivers. He participated in the Irish Rebellion of 1798 and was later executed by British forces for his role in the uprising against English rule in Ireland.

These are just a few examples of notable individuals throughout history who bore the name Gannon, reflecting its deep roots in Irish culture and tradition.