Fitzgerald sits next to 4 phonetic neighbors — Gerald, Fitzpatrick, and Ferdinand are the closest matches by sound. Most share Fitzgerald's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of Gerald"
"of the forest, wooded"
"broad valley"
"bold, wild, fierce"
"settlement by the bridge"
"bright, radiant"
"descendant of Caiside"
"victory"
"great happiness"
"prince, leader (from -mir)"
"broad hillside"
"inspired counsel"
"raider, warrior"
"one who sets free"
"standalone phonetic name derived from letter sounds"
"home ruler, lord of the estate"
"immortal, deathless"
"anglicization of Welsh Llwyd"
"renowned in battle"
"ocean person"
"praised by God (theophoric construction)"
Similar sound: These names share phonetic patterns with Fitzgerald — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Anglo-Norman/Irish origins, giving them the same cultural heritage as Fitzgerald.
Rhythm: Fitzgerald is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.