Celestial (3.5e Feat Type)

[Celestial] Feats
Summary::A feat with the [Celestial] tag can only be taken by a creature who is a Celestial. For this purpose, any creature from any upper plane is a Celestial regardless of its alignment. Further, any elemental or outsider with a Good alignment is a Celestial regardless of its plane of origin. The abilities granted by feats with the [Celestial] tag are Extraordinary abilities unless otherwise stated. Their dual, [Fiend] feats, were originally presented in the Tome of Fiends.

If you prefer slightly simplified rules, a [Celestial] feat can be taken by any Good creature with the Outsider type.