The Thing Upstairs is Berk's lord and master in the British children's show, The Trap Door. No one but Berk knows what "Him Upstairs" looks like as he never leaves his room. Throughout the series, he constantly makes demands of Berk such as cooking his meals, cleaning the castle, and other less savoury tasks like grooming him and cleaning his eyeballs.
While the Thing Upstairs' appearance is never fully revealed, some hints about his physiology are dropped during the series. In the episode The Little Thing, Berk sneaks into his master's bedroom and a flash of lightning illuminates a strange, fleshy heap that could be one of Him Upstairs' appendages. In the episode Slightly Weird, Berk mentions that the Thing Upstairs can fly, implying that he has wings. In the episode Not Very Nice, Berk has to remove one of his master's eyeballs to clean it, and when he tries putting it back, he mutters "Which head did I get it from?", implying that Him Upstairs has multiple heads.