Nix sits next to 4 phonetic neighbors — Nick, Nicks, and Knox are the closest matches by sound. Most share Nix's Germanic cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"water sprite, water spirit"
"my God is Yahweh"
"royal and bold"
"from the town by the sea"
"modern invented variant"
"possibly from Celtic 'avon' (river)"
"divine favor"
"of the forest, from the wood"
"wren bird + meadow clearing"
"elm tree grove"
"character name meaning transformation and power"
"whole, powerful"
"may God protect"
"talon-like, sharp and strong"
"fair-haired hero"
"son of Ty"
"treasurer, keeper of treasure"
"peaceful power"
"Brock's settlement (place name origin)"
Similar sound: These names share phonetic patterns with Nix — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Nix.
Rhythm: Nix is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.