Marco sits next to 4 phonetic neighbors — Marcus, Mario, and Mark are the closest matches by sound. Most share Marco's Italian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"of Mars, warlike"
"strength, force"
"protector of mankind"
"helper, one who helps"
"God hears"
"strong, healthy"
"divine healer"
"lion of God"
"rich spear, lucky warrior"
"Roman pilgrim"
"imperial title, ruler"
"of Lucius"
"God is with us"
"free man"
"brave, manly"
"of the bean growers (Fabii clan)"
"protector of people"
"army man, soldier"
"sun"
"behold, a son"
Similar sound: These names share phonetic patterns with Marco — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Marco.
Rhythm: Marco is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.