The term planet (sometimes referred to as world) is a geographical category. Planets exist in the Great Dark Beyond, which is apparently the term for what we would call "outer space".
The term "world" generally refers to Azeroth itself, other worlds are generally referred to by their names in context to Azeroth.
In geographical hierarchy, worlds contain continents.
- Argus, the homeworld of the eredar race of magic-wielders and their exiled brethren called the draenei.
- Azeroth, the world where most of the action of the Warcraft universe is set.
- Draenor was the homeworld of the orcs, ogres, and other species, and a sanctuary of the draenei. It was destroyed in a cataclysm, but due to a portal through time, it may become accessible again in a form before its destruction.
- Fanlin'Deskor, named in draenei "Amber skies over wondrous rock", was destroyed by the Burning Legion.
- K'aresh, the original homeworld of the ethereals before they evacuated to wander the Twisting Nether.
- Mardum, the remains of a world inhabited by the Burning Legion.
- Nathreza is the home world and base of the Nathrezim. It was completely saturated with demonic energies of the Burning Legion.
- Tarratus, a prison world for rebellious demons in the Twisting Nether.
- Xandros/Remains of Xandros is presumed to be a planet destroyed by the Burning Legion.
- Xerrath was a world destroyed by the Burning Legion as a show of power during the enslavement of Xoroth.
- Xoroth, the homeworld of the dreadsteeds (and possibly the tothrezim).
Argus portal worlds
This section concerns content exclusive to Legion.
- These are worlds seen only in small portion via portals from Argus.
- Hara'samid Sector, Gezhe mentions this while speaking to a Consortium Nether Runner.
- Xarodi sector, Gezhe mentions this while speaking to a Consortium Nether Runner.
Some worlds exist in the Warcraft universe that have not yet been named. Most often we know of their existence because of creatures coming from those worlds.
- Homeworld of:
- Tothrezim (theorized to be Xoroth)
- Demonic hounds (a portal to the planet exists called Death's Door)
- Naaru (if they are not the remains of the Lights of creation)
- Voidwalker (if they are not the remains of the Shadow of creation)
- The Codex of Blood and the summoners of Murmur
- Silithid (if not native to Azeroth)
The draenei passed dozens of worlds and mapped much of the cosmos after they left Argus.
At least seven planets were said to be featured in future patches and/or expansions for World of Warcraft, courtesy of Outland's Dimensional Gateways. In the end however, it appears this idea had been abandoned by the time The Burning Crusade expansion was released. Regardless, there are still a number of different worlds which can be reached in-game, some of which are reached via the same kind of dimensional gateways discussed several years ago.
Remains of worlds
- Outland, the remains of Draenor
- Xandros/Remains of Xandros
- Mardum 
- Niskara, a world controlled by the Burning Legion
In the novel The Last Guardian, the orcs are said to come from a planet (Draenor) on the far side of the Dark Beyond. The sky looked rusty due to the red sun there. ( However, there is also evidence that )Azeroth and Draenor may be in the same star system, as Azeroth can be seen from the courtyard of the Black Temple. It may be a portal or the like since Draenor may be completely in the Twisting Nether (which can be used to pass between points in the universe easily). In the World of Warcraft The Burning Crusade Official Strategy Guide, Azeroth is said to be the "closest habitable world" to Draenor.
Travel between worlds
The only known means of traveling between worlds is through the use of magic, advanced technology, or through the Twisting Nether. These include:
- Dimensional Gateways, such as the Dark Portal.
- Dimensional Ships, such as Tempest Keep.
- Well of Eternity (and by extension, the Sunwell).
- Other portals fueled by various forms of magic.
- ^ a b c d e Matthew Rossi 2013-07-24. Know Your Lore: Worlds lost, worlds unknown. WoW Insider.
- ^ a b c d e Error on call to Template:ref web: Parameters url and title must be specifiedAnne Stickney 2011-05-22. . WoW Insider.
- ^ Draenor
- ^ A&HC, 19
- ^ Prophet's Lesson
- ^ a b Mardum, the Shattered Abyss. Wowhead Legion DB. Retrieved on 2015-12-17.
- ^ World of Warcraft: Illidan, pg. 156
- ^ World of Warcraft: Illidan, pg. 249
- ^ a b <Destroyer of Xandros>
- ^ a b 
- ^ ω τ ϖ
- ^ Medievaldragon 2009-02-09. Chris Metzen & Micky Neilson Pocket Star Books Lore Q&A Video Interview. Retrieved on 2009-02-17.
- ^ LG, 144