Prince Dorrek VIII, later changing his name to Theodore Rufus Altman, was a Skrull-Kree Hybrid who was the son of Mar Vell and Queen Anelle. He was later raised on Earth by a human family. He took the name "Hulkling" due to being a fan of the Hulk and She-Hulk, and was invited by Tony Stark to join the Avengers.
During the Infinity War, Theodore was among the Avengers summoned and rallied by Colonel James Rhodes when Thanos was on the hunt for all the Infinity Stones, including the one that Vision carried. He traveled to Wakanda to take part in the battle against the Black Order's army of Outriders. He tried to stop Thanos, but failed and was among those that survived the culling.