Adaryn -This is a Welsh name meaning "bird"
Adele -A Germanic name meaning "noble".
Aeron -Aeron is a Welsh God of War. His name was derived from the British Goddess of Slaughter Agrona.
Aerona -Feminized version of Aeron, the Welsh God of War whose name was derived from the British Goddess of Slaughter Agrona
Aeslin -Aislin is an Irish name meaning "vision".
Agrona -Agrona is an old Celtic name meaning "battle, slaughter". It was the name of the Brythonic Goddess of war and death.
Aife -Aife is a Celtic name meaning "beauty". It was the name of a great warrior woman of Irish Mythology. She appears in the Ulster Cycle in the tales The Wooing of Emer and The Death of the Son of Aife in which she bears the son of the great Irish hero Cú Chulainn after nearly defeating him in a battle he finally won by trickery.
Aileen -Aileen is a Gaelic name meaning "Pleasant" "light".
Ailidh -Ailidh is a girl's name of Irish/Celtic origin meaning "kind".
Ailill -The name Ailill appears frequently in Celtic lore. It was the name of the husband of Queen Meabh. The name means "elf" in Irish Gaelic.
Aislin -Aislin is a Gaelic name meaning "dream" or "vision"
Alana -Alana is a Celtic name meaning "Little rock/stone" or "Precious" a feminine form of Allen and also a variant of the Hawaiian Malana meaning bouyant.
Alfred -Alfred is an Old English name that means "Elf council"
Allen -A Gaelic name meaning "rock"
Andraste -Boudicca invoked the Goddess Andraste before her revolt against Rome. The name means "invincible".
Aneira -Aneira is a name of Welsh origin meaning "snow".
Angus -Gaelic meaning "One Choice". The handsome Anghus Mac Og of Celtic folklore.
Aranwen -Aranwen is a Welsh name meaning "blessed silver".
Arian -Arian is a boy's name of Welsh origin meaning "silver".
You left off "Cory" which is pretty darned Celtic! lol
I was the only one in Catholic school without a saint's name and a nice nun told me I could be "St. Cory" one day… but I "drifted" and became a nice Pagan boy. lol