God

God, also known as the Almighty, is the creator of the universe and all things in it, who also serves as the narrator of Good Omens.

Metatron is the Voice of God, but an entity in his own right.

Nature
God's true nature or plan cannot be known, since she is ineffable. Not even the most powerful supernatural beings, such as Death, Gabriel, or Satan, can truly understand God.

Trivia

 * God does not physically appear in the show, but serves as the narrator.
 * Metatron makes a physical appearance in "Saturday Morning Funtime"