The Ascension night heron (Nycticorax olsoni) is an extinct night heron species from the genus Nycticorax endemic to the South Atlantic island of Ascension. It is predominantly known from the bone fragments of six specimens found in guano deposits and caves on Ascension Island and described by Philip Ashmole, Kenneth Edwin Laurence Ryder Simmons, and William Richmond Postle Bourne in 2003. The Ascension night heron disappeared in the 16th century. Its scientific name commedorates Storrs L. Olson.