Elysium, or more fully, the Blessed Fields of Elysium, is a strongly good-aligned plane of existence. It is but one of the many alignment based outer planes.
Elysium is a plane of idyllic good and the destination of the souls who sought always to further the cause of good without regard to law or chaos. Elysium is home to many celestial creatures, predominantly the guardinals, a race of celestials native to the plane.