Hadley sits next to 4 phonetic neighbors — Bradley, Radley, and Hartley are the closest matches by sound. Most share Hadley's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"from the heathland"
"fair, white + warrior, hero"
"strawberry grower"
"spear strength"
"exalted, Roman"
"who is like God?"
"the hay town"
"little dove"
"gaming character: adventurous young explorer"
"battle warrior, army in battle"
"aspiration, desire, ideal"
"place name: fortified settlement"
"vigilant, watchful"
"God has heard (via Sam = Samuel)"
"healer"
"dignity, nobility"
"hare land, land of hares"
"great, vast"
"early rain, autumn rain"
"God’s peace, divinely peaceful"
"water-meadow land"
Similar sound: These names share phonetic patterns with Hadley — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Hadley.
Rhythm: Hadley is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.