Sniper, a notable Tindalos.
Tindalos are a species of canine-like creatures that exist in their "Homeland"; a world outside Earth and Equus's current universe.
Physical Anatomy
As described by Garnet, Tindalos are very large creatures that vaguely resemble dogs or wolves, able to grow to the size of a Clydesdale Horse. They have dark fur, four pointed ears, and two tails. Their eyes hold a blue aura, and their irises are edged in a star shape rather than circular.
A notable ability of a Tindalos is their ability to faze through corners, like doorways, which they can even use to travel between Equus and Earth.
It is revealed in the finale of My Little Universe II that Tindalos actually have a "original form" in their own realm. They appear less solid, and have numerous points and jagged edges all over their bodies. Nothing on their anatomy is curved.
History
The first mention of a Tindalos was from Garnet in Tall Tales. A Tindalos was apart of her story: a young maiden, Sophie, created a portal where a Tindalos had appeared through, and it began terrorizing the town. It was found later by Sophie, its leg caught in a beartrap. Sophie, feeling sorry for the creature, helped it out of its binds and, feeling someone care for it for the first time, transformed into a human-like being that vaguely resembled Ruby.
Tindalos first truly appear in All It's Worth, as a pack found Celestia, Luna, and some others nearby their newly-established territory. They tried attacking the princesses, saying that they don't care who they were and they just wanted them gone and back to the town "where they belong". Some tried to figure out what the Gems were, jotting them up either as golems, Elementals, or Homunculi. After failing to hurt any of them, the whole pack simply left, claiming there's plenty more to find in this new world.
Another Tindalos pack makes an appearance in A Promise is a Promise, as the main antagonistic force, the pack belonging to Sniper. The pack originally was in Equestria when they found Trixie, Starlight Glimmer, and Pink Diamond. The leader of the pack, Sniper's Father, was teleported to Earth, Trixie saying that the eyes reminded her of Sapphire somehow. The pack went into Beach City, and were confronted by the Gems, the leading pack member splitting up the already shocked and confused Garnet. The pack tore up a good portion of the town before they had to leave on Smoky Quartz's arrival.
This same Tindalos pack returns during the season 7 finale, arriving in aid of Sniper, and on a revenge mission against the crystal gems. During this mission they cripple Chrysalis of her magic by tearing off her horn. By the end of the fight though, they all retreat when the Pony of Shadows started to attack.
The pack reappears in the finale of My Little Universe II, Sniper explaining how they don't hold a grudge against them like Sniper's father once did, and they allowed them to use one of their dens as a first base.