Riddick sits next to 3 phonetic neighbors — Rick, Derrick, and Hendrick are the closest matches by sound. Most share Riddick's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"powerful ruler"
"one of the Goths"
"son, born of"
"sun, throne"
"land of the Celtic people"
"security token"
"glorious gift"
"gentle birth, beloved"
"sword/fire (brand element)"
"powerful (by association with the watt unit)"
"western settlement"
"God is gracious (via Juan/John)"
"calm, healer"
"unit of luminous flux (scientific)"
"divine strength"
"dweller by the hedged forest"
"remembered by the Lord"
"divine flame, light of the Lord"
"little one, shapely"
"court officer, legal summoner"
Similar sound: These names share phonetic patterns with Riddick — 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 Riddick.
Rhythm: Riddick is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.