An Irish Surname That Crossed the Atlantic as a First Name
Keagan is an Anglicization of the Irish surname Mac Aodhagáin — a patronymic meaning son of Aodhagán, a diminutive of Aodh, the Old Irish word for fire. That fire connection is buried deep under centuries of anglicization, but it's there. At its root, Keagan belongs to the same flame-derived family as Hugh, Aidan, and Mackay.
The name traveled to America primarily as a surname, then made the first-name transition during the Irish-heritage naming revival of the 1980s and 1990s — the same wave that produced Keegan, Kegan, and Kagan. Keagan is one of several competing spellings, which tells you the name was being reinvented by families who knew the sound they wanted but weren't working from a single standard text.
The Spelling Landscape
Keegan is the most common form; Keagan is the second or third most frequent variant. Choosing Keagan signals a mild preference for the a vowel in the second syllable, which gives the name a slightly rounder, more open sound. The difference is subtle in speech but visible on paper. For families who want the Irish sound without the exact common spelling, Keagan threads that needle.
Peak and Plateau
Keagan peaked around 2008, in line with the broader Irish-surname-as-firstname trend. SSA data shows a total count around 8,600 — solid, not massive. The name has been easing back since its peak, consistent with the gradual cooling of the entire Keegan/Kagan family. That plateau means you won't encounter many child Keagans, but you'll meet adults in their late teens and twenties who share the name.
Sibling Pairing
Keagan alongside Declan, Finn, or Maeve makes an Irish-heritage sibling set with real coherence. With more eclectic siblings like Archer or Juniper, Keagan holds its own as the Celtic anchor of the group.