Kullen sits next to 5 phonetic neighbors — Cullen, Collin, and Kullan are the closest matches by sound. Most share Kullen's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"hill, ridge, small summit"
"high, exalted"
"born on Sunday (in some traditions)"
"graced by God"
"master, mister (honorific)"
"God is my strength"
"coal town; settlement by the coal"
"spear warrior"
"son of Roger, famous spear"
"destroyer (possible etymological root)"
"strength, permanence"
"near the thicket"
"He enlightens, God illuminates"
"of the mountain"
"arms (of God)"
"swift as a deer"
"deep valley dweller"
"variant of Karen or Karin"
"who is like God"
"Lord have mercy"
"new house"
Similar sound: These names share phonetic patterns with Kullen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scandinavian origins, giving them the same cultural heritage as Kullen.
Rhythm: Kullen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.