Callahan

An Irish surname striding confidently into first-name territory, Callahan comes from O Ceallachain, descendant of Ceallachan, a name rooted in ceallach, strife or bright-headed. It belonged to tenth-century kings of Munster and a line of Boston politicians before Hollywood borrowed it for a certain squinting San Francisco detective. The name entered the U.S. top 1000 only in the 2010s, part of a wave of multisyllabic Irish surnames claimed by American parents. Three brisk syllables with a percussive opening. Callahan sounds like someone who keeps his word and his receipts, a name built for both the boardroom and the back porch.