Species

=== A ===
* Aaamazzarite
* Aamaarazan
* Aaraandandal slime beast
* The Ablative
* Abominable alien
* Abronian
* Abway
* Acamarian
* Acari
* Aegis
* Aenar
* Aeonian
* Aerolith
* Agellae
* Akaali
* Akker-Takker
* Akoszonam
* Akritirian
* Aksani
* Alcyone
* Aldean
* Aldeberian 
* Alfarian
* Alforia
* Algolian
* Algolian Sithersbac
* Allasomorph
* Alphamatraxan
* Alshain
* Alsheen
* Alsion
* Altairian XIV Bogwoppet
* Althusian
* Altoran
* Ameteli
* Amorta
* Anabaj
* Anar
* Ancetetian
* Anchrola
* Andoran
* Andorian
* Andosian
* Anemone changeling
* Angosian
* Anibusian
* Ankari
* Annari
* Annasaurus
* Antaran
* Antarian
* Antedian
* Anthropophagi
* Antican
* Antidean
* Anurian
* Apalapucian
* Apergosian
* Aquabi
* Aquamen
* Aquan
* Aquarpey
* Aquillian
* Aqu'tican
* Arar Jeck
* Arbazan
* Arboretan
* Arcadian
* Arcateenian
* Arcturian
* Archetryxian
* Archon
* Ardanan
* Areore
* Argrathi
* Argelian
* Argosian
* Arix
* Arkonide
* Arin'Sen
* Ariolo
* Arkarian
* Arretan
* Arrit
* Arrithean
* Arucha
* Ashayan
* Astracane leech
* Atrean
* Atrocious Snowman
* Attow Eel
* Aubertide
* Aulian
* Aurelian
* Australopithecine
* Avanonion
* Axanar
* Ayonian
* Ayt