Michael Iver Peterson (born October 23, 1943) is an American novelist who was convicted in 2003 of murdering his second wife, Kathleen Peterson, on December 9, 2001. After eight years, Peterson was granted a new trial after the judge ruled a critical prosecution witness gave misleading testimony. In 2017, Peterson submitted an Alford plea to the reduced charge of manslaughter. He was sentenced to time already served and freed.

Peterson's case is the subject of the French documentary miniseries The Staircase, which started filming soon after his arrest in 2001 and followed events until his eventual Alford plea in 2017. In 2019, he released his own account of his life since his wife's death in an independently published memoir, Behind the Staircase. The miniseries The Staircase, starring Colin Firth and Toni Collette, also covers the case and its aftermath. Several other documentaries have been produced about Kathleen's death, including a sequel to the 2004 French documentary, podcasts, radio shows and other media.