Companions are highly intelligent magical creatures who look like (but are not) white horses with silver hooves and blue eyes. Companions "Choose" Heralds, and the bond can affect both parties' spiritual and physical well-being.
Though the true nature of the Companions has not been fully revealed, it is inferred they are both the returned spirits of departed Heralds and Companions, as well as divine agents or "avatars" of the gods.
A complete list of Companions is available: Companion list
Firecats are similar to the Companions in that they are the returned spirits of the Sons of the Sun, the head of the church of Karse, effectively the head of the country. Because there are far fewer Sons of the Sun, there are fewer Firecats. Firecats do not make any attempt to hide their nature and use the same name they had in their former life. Rather than choosing a human, firecats are assigned (presumably by Vkandis).
Firecats resemble very, very large Siamese cats with red markings instead of brown, and blue eyes. They have the ability to appear as a common cat, become invisible and to transport themselves long distances by teleportation (called "jumping"). They can also transport objects or humans, although the extra "load" tires them greatly. Like Companions, Firecats are mortal, must eat and sleep and grieve.
The gryphons are a race of primary avian/secondary feline-based creatures created by the Mage Urtho in the time before the Mage War trilogy. Gryphons, which are quadrupedal, winged, sentient beings, have the ability to fly and the potential for both magic and mind-magic. Usually, all four legs of a gryphon end in taloned feet of great strength. In some cases the forefeet are more handlike and useful for fine manipulations.
Gryphons are deadly fighters and, save for a colddrake, there seems to be no creature that is a match for them without the aid of ranged weaponry, magic, a surprise tactic or a large dose of sheer luck. They also work as scouts and messengers, using their superior senses and speed. Two gryphons together (or a single one, supported by weight-reduction magic) are able to carry a harness or a sled with a human for several hours.
The kyree are a race of wolf-like creatures that are found in the Pelagirs region and elsewhere. Kyree have a natural talent for mind-magic, and have the distinction of coming in three genders: male, female, and neuter.
In description the kyree have "rather blunt, wolf-like heads and bodies like a cheetah, with tails and coats like wolves," and they live for "about as long as humans."
This is a race of short lizard-like people allegedly created by accident by one of Urtho's predecessors (The Black Gryphon). The race is known for friendly relations with the Tayledras, as well as making up a substantial part of the population of k'Leshya. The race as a whole has a compulsion to serve, such as cooking and serving of meals and the cleaning and repairing of clothing, pathways, or housing. They are not subservient in this. They are able to use Mind-Magic, and some of them become Healers and Mages as well.
The average Hertasi is described as being about the height of the chest of a man, with a short, stubby snout and short, stubby fingers that are highly dexterous, and covered in pebble-scales of a blue-gray coloration. Hertasi can be extremely timid, though there are exceptions.
The bondbirds of the Hawkbrothers are similar to Companions in that the birds choose the human that they wish to bond with. They bond only with Tayledras or those adopted into a Tayledras clan. All Tayledras are able to speak with their bondbirds mind-to-mind -- however, this is done in a more rudimentary fashion than the way Heralds speak to their Companions. Unlike Companions, many bondbirds may choose to bond to the same human at the same time. This happens most often with flocks of crows.
The Tayledras cultivate a bondbird breeding stock. Bondbirds are allowed to live as wild birds if they wish, but most choose to bond. Bondbirds are generally anywhere from 3 to 10 times the size of their wild counterparts.
The tervardi are a race of flightless, anthropomorphic bird people. Known Tervardi settlements are found among the Tayledras and as members of k'Leshya. They are said to be beautiful singers and musicians. They were once traded as slaves because of their unique and enchanting voices, but the slave trade has stopped since they came under the protection of the Tayledras. It is mentioned in one of the novels that the tervardi are not useful for physical offensive action due to their fragile birdlike physiology.
The dyheli are a race of stag-like creatures with a talent for offensive mind-magic. Dyheli herds are led by the male with the strongest mind; and in times of crisis the leader can and will psychically control the entire herd. Dyheli herds can be found near Tayledras Vales and as part of Clan k'Leshya.
They seem to be universally white-furred and white-horned by all accounts, with highly intelligent eyes, and instead of antlers they possess long, curved horns similar to an antelope.
The tyrill are a race mentioned by the Gryphon Tashiketh in the novel Storm Breaking, and dwell exclusively in Iftel. They are described as being something like the hertasi, only larger in nature. They can speak clearly, but it may be assumed that they have Mindspeech like the hertasi though this is not specified.
The ratha are mentioned in Storm Breaking by the Gryphon Tashiketh, and are described as being "what kyree are to wolves, ratha are to mountain cats"). They can be assumed in reasonable course, then, to possess Mindspeech, since they're compared to the kyree who by virtue of what they are, always have the Gift of Mindspeech.