This is a list of beings, places or events in Celtic mythology.
- Abandinus
- Abarta
- Abellio
- Abhean
- Abnoba
- Achall
- Achtan
- Achtland
- Adsullata
- Aengus
- Aericura
- Aes Sidhe
- Aeval
- Agrona
- Ai
- Aibell
- Aillen
- Aimend
- Ain
- Aine
- Airitech
- Airmed
- Alaunus
- Albiorix
- Alisanos
- Amaethon
- Ambisagrus
- Anann
- Ancamna
- Andarta
- Andraste
- Anextiomarus
- Annwn
- Anu
- Arawn
- Arduinna
- Arianrhod
- Arnemetia
- Artio
- Arvernus
- Aufaniae
- Avalloc
- Aveta
- Badb
- Balor
- Banba
- Beag
- Bebhionn
- Belatu-Cadros
- Belenus
- Belisama
- Blodeuwedd
- Boann
- Bodb
- Bodb Dearg
- Borvo
- Bran
- Branwen
- Brea
- Breg
- Bres
- Brigid
- Britannia
- Bronach
- Caer
- Cailleach
- Camma
- Camulus
- Canola
- Carman
- Cartimandua
- Caswallawn
- Cenn Cruaich
- Ceridwen
- Cernunnos
- Cessair
- Cethlion
- Cliodhna
- Clota
- Cocidius
- Conall Cernach
- Conchobar
- Condatis
- Conn of the Hundred Battles
- Contrebis
- Corb
- Cormac Mac Airt
- Coventina
- Creiddylad
- Creidhne
- Crom Cruach
- Cu Roi
- Cuchulainn
- Curoi mac Daire
- Cwn Annwn
- Cyhiraeth
- Dagda
- Damara
- Damona
- Danu
- Dea Matrona
- Dea Sequana
- Dechtere
- Deirdre
- Dewi
- Dia Griene
- Dian Cecht
- Dis
- Don
- Dwyn
- Dylan
- Edain
- Efnisien
- Elen
- Emer
- Epona
- Eri
- Eriu
- Esus
- Etain
- Ethne
- Fagus
- Fand
- Ferdiad
- Fergus
- Fergus mac Roich
- Fianna
- Finn Mac Cumhail
- Fionnuala
- Firbolg
- Fodla
- Fomorians
- Gae Bulg
- Goibniu
- Govannon
- Grannus
- Gwenn Teir Bronn
- Gwydion
- Gwynn ap Nudd
- Hafgan
- Hooded Spirits
- Icaunus
- Inghean Bhuidhe
- Lasair
- Latiaran
- Leucetios
- Lia Fail
- Llew Llaw Gyffes
- Llyr
- Lud
- Lugh
- Lugos
- Luxovius
- Mabon
- Macha
- Mag Mell
- Mag Tuireadh
- Manannan mac Lir
- Manawydan
- Mannan
- Maponos
- Math Mathonwy
- Matres
- Midir
- Milesians
- Modron
- Mog Ruith
- Morrigan
- Murigen
- Nantosuelta
- Nantosuetta
- Nemausus
- Nemetona
- Niamh
- Nisien
- Nodens
- Nuada
- Oengus Mac Oc
- Ogma
- Ogmios
- Ogyruan
- Olwen
- Plur na mBan
- Pryderi
- Pwyll
- Rhiannon
- Robur
- Rosmerta
- Rudianos
- Sabrina
- Samhain
- Saône
- Segomo
- Sequanna
- Shannon
- Sheila-na-gig
- Shoney
- Sirona
- Smertios
- Sucellos
- Sul
- Tailtiu
- Taliesin
- Tamesis
- Taranis
- Tarvos Trigaranos
- Tethra
- Teutates
- Tir na n-Og
- Tuatha Dé Danann
- Twm Shon Catti
- Verbeia
- Vosegus
- Wild Hunt