Brennon sits next to 4 phonetic neighbors — Brennan, Brendan, and Brennen are the closest matches by sound. Most share Brennon's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"descendant of Braonán (moisture/sorrow)"
"of the valley"
"appointed by God"
"auspicious, favorable"
"one who strides, ranger, wanderer"
"sound, reverberation"
"the Lord is salvation"
"proclaimer of peace"
"son of the right hand"
"one who raids, bold adventurer"
"tube, channel"
"fort, castle"
"the people"
"grey valley or settlement"
"keen ruler, bold king"
"strong ruler"
"one who tends a gate or hatchway"
"beloved, darling"
"high place, island"
"modern coinage from la- prefix and -trell"
"father, head of monastery"
Similar sound: These names share phonetic patterns with Brennon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Irish Gaelic origins, giving them the same cultural heritage as Brennon.
Rhythm: Brennon is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.