The marut first appeared in the first edition in the original Manual of the Planes (1987).
Ehkahk was first mentioned in the original Manual of the Planes (1987) by name only.
The leonal guardinal appears under the celestial entry in the Manual of the Planes (2001).
Manual of the Planes, 2001 Wizards of the Coast, Inc.
His game-statistics, and brief biography, can be found in The Manual of the Planes.
The shadow appeared as a template in the Manual of the Planes (2001).
The firre eladrin appears under the celestial entry in the Manual of the Planes (2001).
The Manual of the Planes suggests a similar but different story.
The goristro (tanar'ri) appears in this edition's Manual of the Planes (2001).
The planes were expanded upon in the original Manual of the Planes, released in 1987.