Callahan
[ˈkæləhæn]Meaning
Anglicized form of Irish Ó Ceallacháin, from Ceallachán, a diminutive of Ceallach
Background Story
Callahan is an Anglicized form of the Irish surname Ó Ceallacháin, which comes from Ceallachán, a diminutive of the given name Ceallach. The surname is Irish and Old Irish in origin. It is a doublet of the surnames Kelly and Kellogg.

Related Names
Conlan
English form of Irish Ó Conalláin, "descendant of Conallán", from Conall
Callam
Recorded as a masculine given name in English
Canute
Anglicized form of the Old Norse name Knut
Cashel
Anglicised form of the Irish word caiseal, meaning "stone fort"
Chayton
No documented meaning in the sources checked
Cheveyo
Clancy
From the Irish surname Mac Fhlannchaidh, "son of the red warrior"
Clenn
Clooney
A surname of Irish origin meaning 'descendant of the warrior'.
Conall
Means "rule of a wolf", from Old Irish cú "hound, dog, wolf" and fal "rule"