Marc sits next to 3 phonetic neighbors — Mark, Marco, and Marcus are the closest matches by sound. Most share Marc's French-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"dedicated to Mars"
"great, venerable"
"counsel, power"
"brook, running water"
"God is gracious (John root)"
"river traveler"
"battle, warrior"
"traveler of peace"
"from Saint Denis"
"from the western direction"
"victorious, crowned one"
"son of Harry"
"divine, godly"
"noble elder"
"wolf counsel (via Old Norse Ralph)"
"roof maker"
"one who cares for others"
"son of the gray-haired one"
"little warrior, young Mars"
"one who lives near the fens or marshes"
"one who brews beer or ale"
Similar sound: These names share phonetic patterns with Marc — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Marc.
Rhythm: Marc is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.