Regan sits next to 4 phonetic neighbors — Reagan, Keegan, and Brogan are the closest matches by sound. Most share Regan's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"little king, of royal descent"
"belonging to the night"
"friend of God"
"the river that swallows all rivers (from Zaire/nzadi)"
"born at daylight"
"God is good"
"vigilant in battle (from Casey/Cathasach root)"
"spring-like, of the spring"
"to carry, to bear"
"gift of God"
"my God is Yahweh"
"bear king"
"reddish complexion"
"homestead on the rock"
"modern phonetic respelling of Caden/Caiden"
"new town"
"thunder and lightning (via Raiden)"
"junior, the younger one"
"anointed one"
"God is perfect, Yahweh is upright"
"steward, household manager"
Similar sound: These names share phonetic patterns with Regan — 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 Regan.
Rhythm: Regan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.