Variant of Keegan, from an Irish surname meaning "descendant of Aodhagán."
Kegan is an Anglicized form of the Irish surname Keegan, itself derived from the Gaelic 'Mac Aodhagáin,' meaning 'son of Aodhagán' — a diminutive of Aodh, the ancient Irish god of fire. Aodh was one of the Tuatha Dé Danann, the mythological divine race of pre-Christian Ireland, and the name survived the Christianization of the island to become one of the most common elements in Irish surnames. Hugh, the English approximation of Aodh, became widespread, but in its Gaelic form the fire etymology remained encoded in names like Kegan and its variants.
As an Irish surname, Keegan/Kegan is associated with County Roscommon and Connacht, where Gaelic families of that lineage maintained their presence through the medieval period. The transformation of Irish surnames into given names — a pattern that produced Brendan, Kelvin, Shannon, and many others — accelerated significantly in the twentieth century, particularly in the United States and Canada, where Irish-American families embraced these forms as a way of honoring heritage while choosing names that worked in an English-speaking context. Kegan with the 'e' rather than the more common double-'e' spelling is a softer variant that gives the name a slightly different visual personality — less surname-ish, more immediately first-name in feel.
It has seen steady use in the United States from the 1970s onward, appealing to parents who want an Irish connection without the more common Patrick or Sean. The buried meaning — a small fire, a divine spark — gives it an understated mythological power.