Karn is a mysterious woodsman who appears in Series One of Ren. He teaches Ren how to use a bow, trades food with her, and gives her the sketchbook in which she draws various things. He is played by Christopher Dane.
At the end of the series, he is revealed to be a, or perhaps the, Mahri'Rai. It is unclear exactly what this role involves, though it leads him to protect Ren from the Kah'nath, who he opposes and who it is stated that he has been hiding from.