He is portrayed by Martin Glade.
As a child, Pit Piestig was very lonely and had no friends, so he often asked Santa on Christmas to bring him a white dog as a friend on Christmas. However, Santa never did this as Pit had an allergy against dogs, and instead all Pit got where plush dogs. This caused him to hate Santa an Christmas, his hatred going so far that, as an adult, he couldn't even say the words Santa or Christmas and instead started to studder when trying.
Pit first acts by sending a letter to Santa in which he asked Santa to quit Christmas this year. Santa and Beutolomäus try to find out whether it was a child or an adult who send the letter, until the postwoman tells them it was an adult, judging on the pen he used. While Santa and Beutolomäus wonder who wrote the letter, Pit watches them through a window, whispering to himself that it was him.
He later comes to Santa's house again when he is alone, pretending that there was a sick child who asked to see Santa himself. Santa believes it and follows him to his flat. There, Pit ties him up, informing him that he whishes Christmas to be cancelled.
For a long time, Beutolomäus and a woman named Katharina, calling herself Kalle, try to find out both Santa's whereabouts and the identity of the kidnapper. Meanwhile, Pit tries everything in his power to prevent them from doing so: When they organize a casting to get a temporary successor, Pit joins under the name Herr Schneckenwitz, planning to simply not delivering any Christmas gifts once he got the job. He and another candidate are the only ones who stay after the rest looses interest when hearing that the job won't be paid. However, even after being able to manage all the other tasks, Pit then gets rejected as he can't say Christmas without stuttering, resulting in the other man winning. Later, Kalle and Beutolomäus try to set an article in the newspaper, asking about Christmas-haters, Piestig sabotages the printers and leaves a message on the computer, saying: "Forget Christmas, Santa stays captured".
However, Pit later makes a mistake when going to a tea shop, trying to buy a cinnamon tea for Santa. The shop owner recognizes the recipe as only Santa buys it, causing Pit to flee. The owner of the shop phones Beutolomäus and Kalle and informs them about the suspicious man. To their , their witness turns out to have a short memory, however they can get a picture of Pit from a security camera. They later broadcast in TV, showing the photo and asking if anyone saw this man, to Pit's shock. Things even turn worse for Pit when, after seeing the broadcast, a girl from another flat named Sophie whom he befriended and even sang Christmas cheers with, realizes what he did and runs away from him.
Finally, Beutoloämus and Kalle are able to figure out his name, due to Beutolomäus remembering Pit's rejected letters when the word "allergy" gets mentioned, and temporarily clashing into a doppelgänger of Pit who tells them that he once met him and believes he lives in one of the houses near his shop. However, when Kalle and Beutolomäus get into the house, Pit locks them in the cellar. They are saved by Sophie after convincing her of Beutolomäus identity by remembering her last christmas whishes. With a second key to Pit's flat, which they got from Sophie who's the caretaker's daughter, they are able to get into the flat, untie Santa and escape. However Santa decides to go back and convince Pit that Christmas is something beautiful, as he thinks that Pit is not a bad person. They then invite Pit to join them on Christmas in Santa's house, resulting in him decorating his flat agin after he just threw the decoration away.
At Christmas, he, Sofie, two policemen who helped Beutolomäus and the newspaper's boss all gather in Santa's house, where Pit apologizes for trying to cancel Christmas, claiming that now he doesn't want to anymore as he finally has friends and is also able to say "Merry Christmas" properly. He then leaves with Kalle and the two start playing in the snow.
Pit's hate for Christmas was so great he couldn't speak the words "Christmas" or "Santa", and instead stuttered every time he tried. However, on Christmas, he is finally able to say it after giving up his hate and having finally found friends. His main motive for planning to ruin Christmas was that Santa never brought him a white dog due to his allergy, therefore he accused him of ruining his only chance for a friend. However, Santa convnced him that this wouldn't have helped anyway, as he tells him a story about a man he, for the purpose of conving, calls Pit. In this story, the boy got a dog, but eventually realized he had no friends, meaning that Pit's wish wouldn't have changed anything.
He also had a very strategic side, always trying to counter any move made by Kalle and Beutolomäus. When they cast a temporary replacement for Santa, he tries to win in order to directly sabotage Christmas, but he gets rejected. When they try to start a newspaper campaign to ask about Christmas haters, he sabotages the machines. And when they put wanted posters of him around he streets, he tries to paint over the photos.
Pit was, as Santa put it, not a bad person by heart and actually befriended Santa, despite stopping him from escaping whenever he tried. This is shown when Santa convinced him to sing with Sophie, or when Pit tried to buy his tea for him. He also found an actual friend in Sophie, who sang Christmas Cheers with him, with Pit leaving the word Christmas for Sophie to sing as he was not able to say it. That's why it was an emotional shock for him when Sophie, after learing that Pit kidnapped Santa, ran away from him.
Despite fearing Kalle and Beutolomäus finding him, he had romantic feelings for Kalle, and she also often stated that she thought he had beautiful eyes. After leaving Santa's house, he and Kalle turned friends, shown when they played in the snow.