Michael Morningstar, also known as Darkstar, is one of the plumber kids thay appear throughtout the course of Ben 10 Alien Force. He appeared in the episode All That Glitters and since because one of the most notable regular villains in the series. He has the ability to drain life force from living beings in physical contact, he gained a grudge against Ben and his team after they accidentally caused him to turn into an awful zombie-like being who has to wear a helmet to hide his face. His plans usually involve gaining back his original face and feeding himself, though he seems to still be interested in feeding from Gwen's vast stores of Anodite energy.
Michael is extremely vain and seems to view all females he comes into contact with as "trophies" (as he called Gwen this when battling her and the others in Couples Retreat. He is also viewed as power hungry and egomaniacal.
Michael is initially depicted as a well-mannered individual who appears eager to help Ben and company. He comes from a rich family, as he states that his family has multiple mansions. How his family acquired such wealth isn't explained but it is known his is the only family which has such wealth, which are armed with a menagerie of Plumber technology. The technology in question is monitoring equipment that uplinks to a variety of networks, which funnels information to him. Part of the monitoring equipment features a communication network between the Plumber badges.
As they travel with him, he shows a very uncaring attitude to others around him. This is evident by his slamming of the door in Kevin's face as well as his remarks to Gwen while they are alone. While Ben and Gwen quickly trusted him, Kevin knew since the beginning about Morningstar's true motivation (partially because of his jealousy, as Michael and Gwen tended to flirt with each other). After a fight with zombified schoolgirls from unknown origin, Kevin guessed that Michael was the one responsible for these zombifications. His guess later proved to be right when Morningstar drained Gwen's energy, becoming nearly unstoppable and easily defeating both Ben and Kevin. However, Gwen proved to have enough will to resist his control, and drained her energy back from him, as well as part of his own, leaving him weakened. His other zombie victims then turned against him, and took back what remained of his energy, leaving him almost desiccated and powerless. His Plumber badge was destroyed by Kevin who states that he doesn't deserve it.