Cosmo is a cosmic wolf, which looks similar to an Earth wolf, that has a teleportation ability, in Voltron: Legendary Defender. When Keith and Krolia found him inside the Quantum Abyss, they adopted the wolf and took him with them on their journey.
Cosmo is loyal, affectionate, and very susceptible to loneliness like many real-life wolves. He is an incredibly brave creature, as he has been shown following Keith into battle repeatedly without hesitation. He also aids Lance and Pidge by frightening the Galra enemies via teleportation in the fighters, though he ends up getting injured. Cosmo also drools quite frequently according to Keith.
Cosmo has the ability of teleportation, with small sparks of blue light appearing/flying around/away from the wolf for when it disappears and reappears. When it travels through the stars, it appears as a blue comet before landing onto a planet or space debris like a meteor would, as it's landing creates a small crater around it. Cosmo is incredibly intelligent, as he has assisted Keith in battle by teleporting him to locations of his master's choice without commands. Cosmo is also smart enough to act as a delivery wolf between lions, teleporting between them to deliver food on Hunk's behalf in mid-flight.