Where does “Callahan” come from?

Callahan is an English surname derived from Irish Ó Ceallacháin, a patronymic from the personal name Ceallachán.

Ancestry of “Callahan”, step by step

Step	Language	Word	Meaning
1	Irish	Ó Ceallacháin	—
2	Irish	Ceallachán	—

Callahan — Etymology, Origin & Word History | Etymology Explorer