Willis sits next to 3 phonetic neighbors — William, Wilson, and Wills are the closest matches by sound. Most share Willis's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"resolute protector"
"heart"
"growth, increase"
"beacon hill"
"of January, born in January"
"peaceful ruler"
"eternal, immortal"
"noble, warrior, of high birth"
"ocean, sea"
"savior, deliverer"
"fair, fair-haired, white"
"liberation, journey"
"dark, dark-featured"
"God supports"
"of the wood, forest"
"short form of Trevor meaning large homestead"
"hollow, empty space"
"beauty, grace"
"peak, summit, apex"
"resolute protector (from Liam/William)"
Similar sound: These names share phonetic patterns with Willis — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Willis.
Rhythm: Willis is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.