There are ten animals in The Blockheads, all of which can be tamed (except the Blockhead, obviously): the donkey (of which it includes the unicorn subspecies, obtained by breeding), the dropbear (also more ambiguously known as wolverines, tree bears, badgers, etc. due to their appearance), the fish, the shark, the worm, the dodo bird, the yak, the scorpion, the cave troll, and the Blockhead.
Donkey[]
The donkey can be ridden by using a carrot on a stick acquired from a Craft Bench. They move freely around and will drop leather and carrots when killed. Several different breeds of donkeys are found: the generic breed is simply known as "the Donkey". Upon intensive breeding, a donkey will gradually sprout horns from the forehead and become perhaps a different species (although still technically a donkey), known as a Unicorn (which is arguably a separate species).
Dropbear[]
The dropbear stays in pine trees and will attack if you try to attack it, nearby it at night or by chopping its' "claimed" tree down. It will also move from one tree to another (sometimes they can climb up fruit trees, albeit this is temporary and often occurs after the player has chopped down its tree and the bear has chased and assaulted the player) from time to time and will even chase and attack the player. It will drop fur and leather when killed.
Dodo bird[]
The dodo bird will spawn dodo eggs: you can pick them up and replace them. These will hatch within 1-3 days. Their lifespan is known to be short and it will drop a dodo leg upon slaughter, which is similar in shape to a chicken's. This meat can be eaten raw or cooked, either on a campfire or an electric stove. Raw Dodo Meat is also used to make dodo stew in said Electric Stove. Like donkeys, dodo birds can be bred: however, these birds will become similar to different resources (i.e., dirt, stone, gold, titanium): when these already-bred birds' eggs are placed and used in the Egg Extractor, they become the material the egg is naturally consisted of.
Fish[]
The fish (ambigious breeds and colors) swims in oceans and lakes. Fish can either be captured with a bucket or with a fishing rod. However, they can also be cooked via a campfire or with said electric stove with Tin Foil. Usually, they spawn in oceans (where there is kelp). Raw Fish is also used to make Fish Curry (the only curry in the game), in an Electric Stove. Added in version 1.2
Shark[]
The shark is an aggressive and dangerous animal. They (also) swim in lakes and oceans, neutrally accompanying their smaller, friendlier companions. Baby sharks can be captured with a bucket. Sharks will hurt you when you are seen by them, so sail in a boat and sail fast before getting caught. When killed, sharks will drop raw fish (the amount you receive depends on the size of the shark): or, very rarely, dyed clothes. In 1.7, the chance of this occurring was drastically improved. Added in version 1.2
Worm[]
Worms move passively move throughout the soil and are never actually seen. While edible, they do not provide much nutrition. They can be used as bait for a dodo. Worms are scientifically an animal, thus, they belong on this list. They are also found when harvesting plants.
Yak[]
Yaks are a neutral, hermaphroditic (intersex) mammalian animal. When milked with a bucket, they provide Yak Milk. Meanwhile, when shaved, they drop Yak Shavings, which can be used to create Plaster: both of these features were introduced in the 1.7 Update.
Scorpion[]
Scorpions spawn (exclusively) in deserts. They are particularly active at night. They have two modes of attack: hitting you with their tail/stinger and shooting poison at you. If you kill them, they will drop 1 to 3 poison. Poison can be used to make a gold poison bow and arrows. They were added in version 1.6.
Cave troll[]
The cave troll lives deep underground and it can be tamed with gold coins. For more information, check out the article.
Blockhead[]
A Blockhead is the only playable entity/character in the game The Blockheads. They can be male or female, white, black, or any other race (or color), and can have several different facial features, as well as a few different types of clothing and a near-infinite amount of color options.