In Path of Exile, Pets are a type of microtransaction. They follow the player but do not participate in combat. A player can have up to two pets active at once. Pets can also be released in a player's hideout. There is no limit to the amount of pets a hideout can store.
Recently, GGG introduced the Monkey Pet. Unlike its corrupted and deadly relatives from the forest areas, this playful monkey would be happy to become your travel companion.
There are also many other pets, like the Elephant Pet, Tiger Pet, Rabbit Pet, Wallaby Pet, Lemur Pet, Cobra Pet, Tortoise Pet, Peacock Pet, Bear Pet and the recently released Beast Pet.
I think that every pet looking better than the Hellion Cub pet that you get with the Alpha Manticore Pack.