Fafhrd and the Gray Mouser are fictional characters created by author Fritz Leiber. They first appeared in the 1930s and are known for their adventures in the fantasy world of Nehwon. Fafhrd is a tall, strong warrior from the cold northern lands, while the Gray Mouser is a clever and agile thief from the city of Lankhmar. Together, they navigate a variety of challenges, including magic, monsters, and treachery. The duo's stories blend elements of sword and sorcery with humor and camaraderie. Their adventures often explore themes of friendship, loyalty, and the complexities of life in a fantastical setting. Over the years, they have become iconic figures in the fantasy genre, influencing many subsequent works.