Roy sits next to 3 phonetic neighbors — Troy, Joy, and Lloyd are the closest matches by sound. Most share Roy's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"red (hair color)"
"helper, one who helps"
"beauty, adornment, grace"
"divine power (from Oswald)"
"he who descends, descent"
"little saint"
"opportunity, happenstance"
"lover of horses"
"gift of God"
"sea-born, born of the sea"
"God of the people"
"from Lucania"
"poet"
"man from South Munster"
"man of peace"
"gift, from the sea"
"first zodiac sign, new beginnings"
"raven"
"delight, luxury"
"strength, brave"
"lover of horses"
Similar sound: These names share phonetic patterns with Roy — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scottish Gaelic origins, giving them the same cultural heritage as Roy.
Rhythm: Roy is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.