Fitz sits next to 3 phonetic neighbors — Fritz, Finn, and Fitz are the closest matches by sound. Most share Fitz's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of"
"of the Dorians"
"bright one, luminous"
"man of law, lawyer"
"crowned one"
"hard metal alloy of iron and carbon"
"wise power"
"hollow, cauldron"
"Broken land, marshy area"
"powerful ruler's son"
"settlement on a Roman road, farm on the paved way"
"valley"
"spiritual essence, animating force"
"descendant of the hound of valor"
"place name: from Kelton"
"flat-topped hill settlement"
"unconquerable, unbreakable"
"resolute protector"
"victory, honor"
Similar sound: These names share phonetic patterns with Fitz — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Norman French origins, giving them the same cultural heritage as Fitz.
Rhythm: Fitz is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.