I've mentioned a few races in the last chapter of Magician, here's part of the index which describes them.
Other races and worlds.
Æsir (Human). Small confederation of six Earths of which Valaskjalf is their capital. Fought the Tuatha Dé Danann for over 1,000 years until the Tuatha Dé Danann gave it up as a bad job, much to the disappointment of the Æsir who were quite enjoying the fight. Their society is extremely class conscious with a system of prenoms or titles defining upper and lower classes. Mages work openly with the Æsir government but are not in charge in so far as anyone else appears to be either.
Anasazi (Human). Small pastoral society with a preponderance of very powerful Mages, peaceful but very isolationist.
Craebh Ruadh (Human). An Earth where Mages rule ordinary humans, though quite benevolently for the benefit of all. Hostile to the Coalition of the Pure who hoped to find support amongst them but managed only to alienate themselves and earned enmity by assassinating the leader of the Craebh Ruadh who had opposed their proposals.
Djinni (Non-human). A world where evolution took a very different track. The Djinni are a non-technological magic using society, larger than humans and saurian in appearance. They have no interest in any other world, race or society, simply desiring to be left alone on their world.
Doppelganger A race created from a single cell organism by the Sidhe to infiltrate and destroy human civilisations and resistance from within. Able to take on any shape or form within certain mass limits. When imitating a human they ingest the host body taking the memories as well as the physical shape. They are, like other life forms, partially magical in nature and capable of using magic effectively, though they generally are not as powerful as a human Mage. Parthogenetic in nature using pseudogamy in which the inferior breeder provides the genetic material to 'fertilize' the superior but does not add to the inheritance of the genetic code. Deciding which is the superior and inferior often causes doppelgangers to fight and kill each other and hence their numbers are low; which, for humanity's sake, is probably a good thing as they are extremely dangerous to be in proximity to.
Dvergar A hybrid race of homo-sapiens and homo-neanderthalis. Once the jewellers and miners of the Sidhe, then abandoned by them as the Sidhe retreated from our world. The majority have now resettled on their own world (un-named) leaving behind a small core who await the return of the Sidhe (and refusing to believe what that would entail).
Loegria (Human). Although a small country of another Earth, Loegria has become the name of that Earth to those Mages who know of it. High in technology in the region of 20 to 100 years in advance of our own Earth in certain areas.
Maraú-Uxuí (Non-human). World of magic using spiders, friendly though isolationist and deeply creepy.
Mazdan (Non-human). An Earth in which the dominant life form developed from ursine stock. They are peaceful, isolationist, though seriously dangerous if provoked as the Tuatha Dé Danann found out to their cost when they attempted to invade, losing their entire force and having to use desperate measures to close the gateway to their world when the Mazdani sent through a punitive expedition themselves which left the Tuatha Dé Danann world of Finias devastated to the point where it was almost abandoned. An uneasy peace now holds between the two races and the Tuatha Dé Danann tread very carefully around the Mazdani.
Nazca (Human and Neanderthal). One of only two (known) Earths where homo-neanderthalis survived, though very much as second-class citizens. Isolationist in nature and ruled by what appears to be some form of criminal secret society backed up by some very heavy duty Mages.
Ogdoad (Non-human). Earth where evolution took a different path. They are non-technological paranoid magic users, vaguely sauroid in appearance, but producing live births. Will avoid all contact with other Earths except in extreme circumstances, often committing ritual suicide to avoid pollution from contact.
Olorun (Human). An Earth where religion rules via theurgical magic. Has little interest in other Earths with non-believers.
Phaëtoni (Human and Neanderthal). The other (known) Earth where homo-neanderthalis survived. Very much in the majority over homo-sapiens, though ruling them benevolently. A very peaceful society with little or no magical use. They are allied to the Craebh Ruadh in order to prevent incursions by the Tuatha Dé Danann.
Rutasi (Human). An Earth ruled by a world spanning empire whose Emperor is treated as a living god. Highly militaristic, though not expansionist, simply using them to keep the populace in line. Pretends that other worlds do not exist, though their Mages will open a dialogue if there's something that they want or need.
Tír na nÓg (Non-human). Home of the Sidhe where they live in splendid isolation waiting for the day where they can retake the worlds of humanity (and others) from whence they were driven out due to their excesses. Run by two courts Seelie and Unseelie whose aims though differing in method are all to do with reclaiming the lands they lost one way or another. They are a dying race as immortal to the extent that they do not die naturally. They have simply stopped breeding. Without anyone other than themselves to dominate it has warped their civilisation into one of perpetual blood feud and petty spite.
Tuatha Dé Danann (Human). Expansionist militaristic society holding four Earths in its autarchy (Falias, Gorias, Finias and Murias). Technologically advanced up to about the level of 1800 AD, though uses magic to supplement its military and so are considered very dangerous.
Tiamati (Human). A world where mysticism apparently runs riot and Mages are the highest of the high. Largely peaceful though find it difficult to comprehend the Mages of other Earths, nor cope with being treated as their equals.
Vedic (Non-human). Denizens of three Earths where evolution took a far different path. Technologically advanced but unstable as tribal warfare is rife, though rarely gets out of hand. The Council prison planet of Kurukshetra was a Vedic world until they destroyed much of the biosphere in a civil war. Human sized though insectile in appearance, four arms and tusks.
Völuspá Gnomish craftsmen, highly skilled in the mechanical arts, shy, retiring but able to use a form of glamour to live amongst or avoid humanity. Possibly the legend behind the Santa Claus elf myth.
There are a massive number of uninhabited Earths or rather unclaimed ones on which Mages reside, these also include a one way world maintained by all races to house Doppelgangers captured by the various Mage communities.
Note, this is not the complete index.