Several types of Animals can either be raised, adopted, or simply observed throughout the game (see Other Creatures at the end of this page). Animals that live on The Farm will require specific Farm Buildings to be purchased from Robin at the Carpenter's Shop. Most animals can be purchased or adopted from Marnie at Marnie's Ranch, while others require the player to have met specific criteria in the game to become available.
All animals that live on the farm can earn Friendship points with the player, excluding the horse. For some animals, reaching a higher friendship level will unlock the ability to drop different Animal Produce or the ability to drop other items as gifts (from Pets). Higher friendship levels with farm animals will increase the quality of the items they produce, excluding pigs and the horse.
Once the player has a large amount of farm animals, petting them and collecting their produce each day can become quite time-consuming. The Auto-Petter and Auto-Grabber can perform these tasks each day, saving a fair amount of time in the player's daily routines. Note: the Auto-Grabber will reduce friendship points by a small amount each day. By petting them daily or placing the Auto-Petter in the barn or coop, the point reduction is nullified and the animal will continue to gain friendship points.
Non-egg laying farm animals can reproduce to make baby animals and can be toggled on or off in the animal's menu, which is accessed by right clicking on the animal. Egg laying animals do not reproduce in this way, but can instead have their eggs hatched in an Incubator for babies. Baby animals can be pet every day to increase friendship, but will not begin producing goods until they reach adulthood.
Coop Animals[]
Coop animals currently include various types of Chickens, Dinosaurs, Ducks, and Rabbits. Most may be purchased from Marnie at her ranch. Coop animals will drop their produce on the floor of the coop to be collected each morning, or can be automatically collected by an Auto-Grabber that is placed inside the coop.
Chickens[]
There are five different types of chicken that can be acquired. Standard Chickens can be either white or brown and become available to purchase from Marnie for 
800g each as soon as the player has their first coop built. Void Chickens, Blue Chickens, and Golden Chickens are not initially available and each have unique ways of obtaining them.
All types of chickens can be hatched from their respective egg types in the Incubator of a coop, excluding Blue Chickens. Chicken types other than the white and brown variants require a Big Coop or Deluxe Coop.
See their respective article pages for more information about each type of chicken.
Dinosaurs[]
Dinosaurs require a Big Coop or Deluxe Coop and will lay Dinosaur Eggs, which can be hatched in the incubator for more dinosaurs. The dinosaur egg is also an artifact required to complete the Museum's collection, but considering they are fairly rare to find and cannot be purchased from Marnie, it is recommended to hatch the first dinosaur egg found and then wait until a dinosaur matures and begins laying more eggs.
Ducks[]
Ducks are another coop animal available for purchase from Marnie for 1,200g each. They will lay Duck Eggs, which can be hatched in the coop's incubator for more ducks, and may also produce Duck Feathers after their friendship level with the player is high enough.
Rabbits[]
Rabbits can be purchased from Marnie for 8,000g each, and will require a Deluxe Coop to become available. They will produce Wool and after reaching higher friendship with the player, may also periodically produce a Rabbit's Foot. Rabbit's can have reproduction toggled on or off in their animal menus.
Barn Animals[]
Barn animals include two types of Cows, Goats, Ostriches, Pigs, and Sheep. Excluding the Ostrich, these animals can all be purchased from Marnie at her ranch. Ostriches are the only barn animal that will drop their eggs on the floor of the barn and all other barn animal types require either the Milk Pail or Shears to have their produce collected, or the Auto-Grabber if placed inside the barn.
Cows[]
Cows may come as either white or brown, and may be purchased from Marnie for 1,500g each after the player has built their first barn. They will produce standard or large Milk depending on their friendship level, which can be collected daily using a Milk Pail or automatically with an Auto-Grabber.
Goats[]
Goats are another barn animal that can be purchased from Marnie for 4,000g each and require a big or deluxe barn upgrade to become available. They will produce standard and large Goat Milk, which can be collected in the same way as milk from cows.
Ostriches[]
Ostriches are a barn animal that produce Ostrich Eggs, and cannot be purchased from Marnie. An ostrich egg must first be acquired either from solving Secret Note #10 or obtained in the Volcano Dungeon as rare loot from chests. The egg can be hatched in the Ostrich Incubator that is placed inside a barn. The recipe to craft the incubator is rewarded by Professor Snail on Ginger Island after completing the Island Field Office archaeology collections and survey.
Pigs[]
Pigs are available for purchase from Marnie for 16,000g each after the player has upgraded a barn to a Deluxe Barn. Unlike other farm animals, pigs do not drop animal produce. They instead dig up Truffles when they are let outside of the barn on non-rainy days. The quality of the truffles depends on the player's Foraging skills, not their friendship level.
Sheep[]
Sheep are purchased from Marnie for 8,000g each, and will produce Wool that is collected using Shears or automatically from the Auto-Grabber.
Pet Animals[]
There are three types of Pets available in the game, including Cats, Dogs, and Turtles. Dogs and cats both have 5 different variations to choose from and turtles have two. The first dog or cat received is free from Marnie (the one chosen during Character Creation) with additional pets becoming available to purchase after the player has earned max friendship with the first pet, or after progressing to year 2. Cats and dogs each cost 40,000g, while turtles cost 60,000g, or 500,000g for an iridium turtle.
Available Pet Bowls are assigned to new pets automatically. Pet bowls aren't a requirement to have more pets, but pets will become upset and lose friendship over time if there isn't one available. Friendship points for pets can be earned by petting them and filling their pet bowl with water each day using a Watering Can. Pets that have reached max friendship level will not lose friendship if they aren't pet daily, but will begin losing points if their bowls aren't filled with water.
After reaching max friendship with any pet, there is a 20% chance (after the player pets them) that they will drop a varying quantity of an item selected at random from a pool of items unique to that type of pet.
See each pet's article page for more information about them, and the potential gifts they may give.
Horses[]
A Horse is automatically obtained with the purchase of a Stable from the Carpenter's Shop and costs 10,000g, 
Hardwood (100), and 
Iron Bar (5). A horse can be ridden by the player around almost any region of the game and significantly increases travel speed, which can be further enhanced if the player drinks coffee and/or feeds a carrot to the horse.
See the horse's article page for more information.
Other Creatures[]
A wide variety of animals and critters can be observed in various places throughout the game, including Birds, squirrels, wild rabbits, frogs, lizards, Butterflies, bats, fireflies, and many more.
Not including butterflies and fireflies, these creatures will flee from the player if approached, disappearing among various environmental objects like Trees and shrubs that are nearby. They cannot be interacted with by the player, except for the Prismatic Butterfly.
Lava Monkeys[]
Lava Monkeys are seen in the Volcano Caldera at the peak of the Volcano Dungeon on Ginger Island. They are always smiling or have their eyes closed, happily relaxing in the cozy, molten rock. A secret can be discovered through a unique interaction with one, if it's close enough to the player. See the Volcano Caldera page to find the solution.