Thomas Peter Thorvald Kristian Ferdinand Mortensen (August 16, 1882 – April 25, 1998), known as an adult as Christian Mortensen, was a Danish-born American supercentenarian who lived to age 115 years and 252 days,[1] and was believed to be the second-oldest man in history, after Japanese Shigechiyo Izumi (claimed to be born June 29, 1865 but was most likely born in 1880) who died on February 21, 1986 at the claimed age of 120 years, 237 days.[2] However, Izumi's claimed record was officially debunked in 2012, and later in 2023 even the claimed age record of American Mathew Beard (claimed to be born 9 July 1870) who died almost exactly one year before Izumi at the claimed age of 114 years, 222 days,[3] and Mortensen is therefore verified to have been the first man who lived to age 114 as well as the only man who lived to age 115 before Emiliano Mercado del Toro's 115th birthday on August 21, 2006, and the oldest man in history until December 27, 2012 when his record was broken by Japanese Jiroemon Kimura.
Mortensen was baptised in Fruering Church on December 26, 1882.[4] Besides his baptismal record, other records include the 1890 and 1901 census enumerations in Denmark, and church confirmation in 1896.[5] He was the world's oldest validated living man between January 20, 1994 and April 25, 1998.[2]