Willian sits next to 3 phonetic neighbors — William, Wilson, and Guillermo are the closest matches by sound. Most share Willian's Portuguese-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"resolute protector"
"from the Antonius clan"
"male, manly"
"little messenger of God"
"graceful, elegant"
"victor's crown"
"may God strengthen him"
"dark-complexioned"
"God is salvation"
"father of many"
"renowned king"
"copper island native"
"God is my strength"
"God has given"
"red (from Spanish rojas)"
"little free man, dear little Charles"
"flat-footed"
"son of God-peace"
Similar sound: These names share phonetic patterns with Willian — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Willian.
Rhythm: Willian is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.