Reference: Supplementary Fantastic Beasts

Most records of fantastic beasts are based on Newt Scamander's 2017 edition of Fantastic Beasts and Where to Find Them, which documented eighty-nine species of fantastic beasts (with each type of dragon counted as one species). However, this was not a complete and exhaustive list of the fantastic beasts in the Harry Potter world. The omitted creatures were likely left out for the following three reasons:

1. Political pressure: Some fantastic beasts were used by the magical authorities of their places of origin—the Ministry of Magic or MACUSA—as guards, scouts, and so on, so they did not want relevant knowledge to leak out. Examples include the Greek Ministry of Magic and the Three-headed Dog, and the French Ministry of Magic and the Matagot.

2. Limited space: Scamander positioned Fantastic Beasts and Where to Find Them as an introductory book on magizoology, not an encyclopedia akin to a complete compendium of fantastic beasts, so he did not wish to include rare and obscure creatures.

3. Still undiscovered: Although Fantastic Beasts and Where to Find Them was published in the Muggle world in 2001, its contents corresponded to the edition Harry bought in 1991—that is, one published before 1991. Some fantastic beasts may not yet have been discovered at the time.

Here are some of the omitted fantastic beasts:

[Original Works]

1. Three-headed Dog—Hagrid bought one from a Greek man and named it Fluffy. (Sorcerer's Stone)

2. Bicorn—Its horn was an important ingredient in Polyjuice Potion, and its head also appeared on Durmstrang's school crest. (Chamber of Secrets)

3. Double-ended Newt—A wizarding pet sold in the magical creature shop in Diagon Alley. (Azkaban)

4. Cockatrice—In 1792, its rampage injured many people during the Goblet of Fire, causing the tournament to be canceled from then on until it was revived in 1994. (Goblet of Fire)

5. Blast-Ended Skrewt—A new breed cultivated by Hagrid in 1994, born from the crossbreeding of a Manticore and a Fire Crab. (Goblet of Fire)

6. Wood Nymph—Mentioned in Fleur's dialogue; they sang for entertainment at Beauxbatons' Christmas banquet. (Goblet of Fire)

7. Hydra—Mentioned in Snape's dialogue. He described the Dark Arts as being like a Hydra: cut off one head, and two more would grow back. Hydras also appeared in Ancient Runes, representing the number "nine." (Half-Blood Prince)

[Fantastic Beasts Films] (Most of the Chinese names were translated by the author, with reference to materials from the Harry Potter Chinese Wiki.)

1. Abarimon—A humanoid creature with hind legs, one of the Arcanus Circus performances.

2. Firedrake—A small flying lizard that could shoot sparks from its tail, one of the Arcanus Circus performances.

3. Oni—A horned demon from Japan, one of the Arcanus Circus performances.

4. Homo amphibia—Subterranean people from Muggle legend, one of the Arcanus Circus performances.

5. Matagots—Small cat-like creatures that guarded the French Ministry of Magic. When struck by a curse, they continuously split and multiply, becoming ever more numerous.

6. Chupacabra—A small vampiric lizard-man and Grindelwald's pet.

7. Glow Bugs—Small glowing insects used by Newt for illumination, and among the pets in Newt's suitcase.

8. Marmite—A hybrid of mite and squid, and among the pets in Newt's suitcase.

9. Swooping Evil—A magical creature resembling a butterfly. When not flying, it curled into a spiny chrysalis. It fed on human brains, and its venom, when diluted, could remove unpleasant memories. One of the pets in Newt's suitcase.

10. Zouwu—A giant cat-like creature with five colors on its body, originating from China. It could instantly travel within the French Ministry of Magic's anti-Apparition perimeter, and was one of the pets in Newt's suitcase.

11. Leucrotta—A moose-like creature with an enormous mouth, and one of the pets in Newt's suitcase.

12. Water Dragon—Appeared only in Newt's dialogue, when he suspected that a Water Dragon was lurking in the Paris sewers.

[2014 Quidditch World Cup—From Daily Prophet Dispatches]

1. Hoo-hoo—The Japanese team's mascot.

2. Genie—The Ivory Coast team's mascot was a Water Genie skilled at dancing. This did not rule out the possibility of other Genies existing.

3. Selma—A serpent-like creature that was fierce and fond of human flesh, the Norwegian team's mascot.

4. Sasabonsam—A vampiric humanoid creature from the African jungle that went mad at the scent of blood, the Nigerian team's mascot.

(Other mascots that appeared, such as Dukuwaqa and Curupira, were classified by the author as "Beings." Sasabonsam's bloodlust and aggression led to its classification as a beast.)

[Pottermore]

1. Jackalope—Its horn was one of the common wand cores in North America.

2. Rougarou—Its hair was one of the common wand cores in North America. Wands with this core were suited for casting the Dark Arts.

3. Sasquatch—A large-scale riot in 1982—leading the author to infer that they possessed intelligence and aggression—forced MACUSA to relocate to New York.

4. White River Monster—Its spine was once used to make wand cores in the early twentieth century.

5. Wyvern of Wye—A lesser dragon with only two legs that could breathe fire. It was slain by Sir Cadogan in the Middle Ages.