Callan sits next to 3 phonetic neighbors — Callen, Callie, and Kalan are the closest matches by sound. Most share Callan's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"battle, rock"
"grey-haired one"
"Yahweh is merciful"
"God is my judge"
"black, dark-haired"
"carp fish; symbol of perseverance and good luck"
"loyal"
"strong, resilient one"
"little king, royal one"
"son/daughter of Kenneth"
"dark beauty"
"happiness, joy"
"noble strength with grace"
"from Britain, a Briton"
"modern invented name combining Az- and -lynn (lake)"
"Gaelic speaker"
"holy, sacred plant"
"foreign woman, stranger"
"golden, made of gold"
"safe harbor, place of refuge"
"sea warrior"
Similar sound: These names share phonetic patterns with Callan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scottish Gaelic origins, giving them the same cultural heritage as Callan.
Rhythm: Callan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.