Callaghan sits next to 3 phonetic neighbors — Callahan, Calahan, and Sullivan are the closest matches by sound. Most share Callaghan's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"lover of churches"
"slender, narrow"
"God is my reward"
"power of the sea"
"son of Faelan (the little wolf)"
"creative American original"
"victorious people"
"from the Leyden region"
"son of Oeneus, warrior"
"from Arcy, Norman town"
"short form of Christopher"
"from the mountain"
"Carl's island or stronghold"
"warrior (via samurai resonance)"
"God is gracious"
"from the rippling water"
"son of Ben"
"handsome, born of fire"
"narrow strait, channel"
"modern coinage"
"great lord"
Similar sound: These names share phonetic patterns with Callaghan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Irish Gaelic origins, giving them the same cultural heritage as Callaghan.
Rhythm: Callaghan is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.