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"
"the fifth"
"rye grain"
"son of the home ruler"
"little dark one"
"descendant of the shouter (herald)"
"happy estate"
"of the forest, wooded"
"great happiness"
"bright, fair"
"from the hills"
"rich, powerful ruler"
"friend of the army, warrior's friend"
"help, strength"
"remembered by God"
"keeper of enclosed parkland"
"gate attendant, herald"
"most high, exalted one"
"descendant of Bradan (salmon)"
"curly-haired"
"Wise one, a sage person"
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.