When Niedamir was a very young king he was a participant in the hunt for the golden dragon, Villentretenmerth, and Gyllenstiern's employer. Niedamir joined the hunt due to his desire to conquer Malleore - after the sudden death of its prince, it was left in the hands of his daughter, a princess that the nobility of Malleore was trying to use to increase their power, a thing that would be rendered more difficult should she marry.
Niedamir had asked for her hand, but the nobles attempted to prevent any such union by using a conveniently discovered ancient prophecy which stated that the princess could only marry a man who had slain a dragon. Niedamir heard of the dragon of Barefield, Myrgtabrakke, and so set out on the hunt to slay her, thinking it a way to seize control of the principality while still conforming to the demands of the nobility.
Some time afterwards, he successfully seized control of Malleore and Creyden, forming the Hengfors League. During the second Northern war, the Hengfors League under his control remained neutral with respect to both sides including Nilfgaard.
In The Hexer he was played by Rafał Królikowski. He appears in the movie and in episode 4 of the TV series, entitled "Smok" ("Dragon"), based on the short story "The Bounds of Reason" in which he first appeared.