Alexei sits next to 5 phonetic neighbors — Alexis, Aleksei, and Alexey are the closest matches by sound. Most share Alexei's Russian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"defender, helper of mankind"
"iron-willed, strong"
"flame, bright"
"strong man, warrior"
"proclaimer of peace"
"gift of God"
"champion of the people"
"people's triumph"
"white, silver (ancient root)"
"who is like God? (no one!)"
"associated with Vladimir Lenin, revolutionary leader"
Similar sound: These names share phonetic patterns with Alexei — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek 'alexein' origins, giving them the same cultural heritage as Alexei.
Rhythm: Alexei is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.