Marvel's What If..? Episode 2, What If... T'Challa Became a Star-Lord?, celebrated the hero that he is not only in Wakanda, but also, in the whole universe, and he is a well-known one, having fans from different races. His encounter with The Collector, though, gave him a chance to reunite with something from Earth, a dog, which he later adopted, but who is that?
Warning! This portion may contain spoilers for Marvel's What If..?. Read at your own risk!
Who is the Dog T'Challa Adopted in Marvel's What If..?
The whole episode of What If...T'Challa Became a Star-Lord? undoubtedly shown how much of a hero T'Challa is throughout the universe, and despite the loss of the actor behind the character, hearing him once more feel as if he is still alive and with us right now. The story glorified him as a savior of all sorts, including a dog he saw in the collection of Taneleer Tivan, which he later adopted.
The adorable pup is none other than Cosmo the Spacedog and how he formed part of the collection of Taneleer Tivan is anybody's guess. Cosmo was inspired by a real-life pup: a USSR dog astronaut named Laika who was sent to space by the Soviet Union sometime in the 50s.
However, in Marvel Comics, Cosmo the Spacedog is a powerful one considering that he is a telepathic Soviet dog who acts as the security chief of Knowhere, and he also became a member of the Guardians of the Galaxy. He started as a test animal who drifted in space then got a mutation from cosmic rays until he arrived in the head of a dead Celestial.
This is not the first time Cosmo the Spacedog made an appearance in the MCU. He already had a cameo in both Guardians of the Galaxy and Guardians of the Galaxy Vol. 2, which, itself, makes his appearance in the episode of T'Challa being Star-Lord a sensible one considering that he was always seen with The Collector as part of the various collections he had.
In the episode, T'Challa had to fight The Collector who wanted him to be part of his collection but knowing that he won't back down just like that, Taneleer Tivan did not give up without a fight. In this alternate reality, The Collector was strong and feared upon, having a collection so vast, it could almost take up all of Knowhere. Still, his weakness could be pointed to his assistant, Carina, who betrayed him later in the episode.
While Cosmo the Spacedog seems a cute canine friend to T'Challa, having him in the episode makes it more worthwhile as he symbolized a stray still chosen and kept, like how T'Challa is for Yondu, that despite the Ravagers taking the wrong kid, he kept him and showed him an adventure he would never forget in his life.