Sully sits next to 4 phonetic neighbors — Sullivan, Solly, and Sulley are the closest matches by sound. Most share Sully's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"descendant of the dark-eyed one"
"God strengthens"
"flame of God"
"God is gracious"
"ancient, enduring, long-standing"
"constructed blend name"
"short form of Walter"
"bright-headed"
"circular stone fortress"
"of the gods"
"famous wolf"
"creative American original"
"most beautiful"
"hill, eminence (via Brian)"
"from Hadria, near the Adriatic"
"literary name: the ranger Aragorn"
"Winda's homestead, windy village"
"lord of the marches, border lord"
"slender, narrow"
"descendant of Braonán (moisture/sorrow)"
"one who carries Christ within"
Similar sound: These names share phonetic patterns with Sully — 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 Sully.
Rhythm: Sully is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.