Sven Elvestad (7 September 1884 – 18 December 1934) was a Norwegian journalist and author. He is best known for his detective stories, which were published under the pen name Stein Riverton and translated to several languages, including German and English. Elvestad was born as Kristoffer Elvestad Svendsen, in Fredrikshald (now Halden), a small town near the Swedish border. After, as a young office boy, embezzling money from his employer, he changed his name and started a new life as a journalist in Kristiania (Oslo). The Norwegian Riverton Prize is named after him.