Alonso sits next to 3 phonetic neighbors — Alfonso, Alonzo, and Antonio are the closest matches by sound. Most share Alonso's Spanish-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"noble and eager, ready for battle"
"supplanter, one who follows at the heel"
"dark-haired, tawny"
"glory of the land"
"man, warrior"
"he will awaken"
"greatest one"
"like unto God"
"hater of injustice"
"lion hardy"
"belonging to Mars, the war god"
"consecrated to God"
"from the Egnatius family name"
"noble bright (adal + beraht)"
"elf warrior"
"immortal, divine"
"battle to the death, determined fighter"
"elf counsel, wise counselor"
"son of the south"
"famous land, renowned territory"
Similar sound: These names share phonetic patterns with Alonso — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic via Visigothic origins, giving them the same cultural heritage as Alonso.
Rhythm: Alonso is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.