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"
"heart, mind"
"wayfarer, wanderer"
"religious official, one who performs sacred rites"
"slender, narrow"
"apparent, visible"
"fashionable, sharp (modern connotation)"
"son of Day, child of daylight"
"clean, righteous"
"new house"
"beloved, praised"
"faith, religion"
"the kamani tree (Calophyllum inophyllum)"
"rocky outcrop, tor"
"pure strength"
"from the gray estate"
"asked of God, prayed for"
"God persists, God will prevail"
"sun"
"world ruler"
"the free one, freedom"
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.