Dennis Pearson is a character in the U.S. television series Angel, played by BJ Porter.
Dennis first appeared in the Angel episode "Rm w/a Vu", in the first season. Cordelia moved into an apartment where Dennis and his mother, Maude Pearson, once resided. The Angel Investigations team, which consisted of Angel, Cordelia Chase, and Doyle at the time, discovered that the apartment was haunted by Dennis' mother Maude.
After some investigation, the gang discovered that Maude Pearson had died of what was believed to be a heart attack on the same day that her son had disappeared. The group came to the conclusion that Dennis had killed his mother in order to be with a woman she didn't approve of. However, after being haunted by the ghost of Maude, Cordelia broke down a wall in her house, revealing the still tied-up body of Dennis Pearson. The team deduces Maude had tied her son up when she learned that he was leaving her to be with his girlfriend, subsequently building a brick wall and trapping him inside, where he suffocated to death. When Cordelia broke down the wall, it unleashed the spirit of Dennis, who destroyed his mother's ghost. Because the ghost of Dennis still inhabited the apartment, and Cordelia refused to move out, Dennis then resided with Cordelia as an invisible, and rather benevolent, roommate; in Birthday he was even seen to have prepared a surprise party for her by himself.
In the season 3 episode Waiting in the Wings Cordelia states that the best romantic action she can get nowadays is "an invisible ghost who's good with the loofah", hinting at a deeper relationship than just roommates.
Their "living" situation continued until Cordy came back from being a higher being in season 4, with Dennis never being seen again after a scene where he 'confronted' Angel, Gunn and Fred about taking Cordelia's possessions out of her apartment. It can be assumed that Dennis is still 'haunting' the apartment that Cordelia used to live in. In a reference to Star Wars Episode I: The Phantom Menace, he has occasionally been referred to as "the phantom Dennis."
Dennis's usually remains invisible and unlike his mother doesn't possess a visible human form. However when he did manifest physically he took the form of a ghostly face surrounded by tendrils of light.