Knecht Ruprecht a frightening character, dressed ruggedly. He carries a sack and a birch rod. His sack is either filled with apples, nuts and other small gifts for good children, or it is to (threaten to) put the naughty children into. Likewise, he has his birch to punish the bad children, but in practice mostly to threaten it and not to actually spank them.
Sometimes the figures of Knecht Ruprecht and St Nicholas are also merged into one.
Knecht Rupprecht threatens a girl who failed to say her prayers. From Die Struwwel-Liese (1890).