Þórðarson is a surname of Icelandic origin, meaning son of Þórður. In Icelandic names, the name is not strictly a surname, but a patronymic. The name is sometimes written Thordarson and may refer to:
Björn Þórðarson (1879–1963), Icelandic politician; Prime Minister of Iceland 1942–44 Chester Thordarson (born Hjörtur Þórðarson) (1867–1945), inventor who held nearly a hundred patents Fridrik Thordarson (1928–2005), Icelandic linguist Guðjón Þórðarson (born 1955), Icelandic professional football manager Guðlaugur Þór Þórðarson (born 1967), Icelandic politician; member of the Althing since 2003 Óláfr Þórðarson (1210–1259), Icelandic scholar and skald Ólafur Þórðarson (footballer) (born 1965), Icelandic professional football player Sigurdur Thordarson (born 1992), FBI informant against Julian Assange Sigurjón Þórðarson (born 1964), Icelandic politician Sigvatr Þórðarson (fl. 11th century), court poet to kings of Norway Stefán Þórðarson (born 1975), Icelandic professional football player Stefán Teitur Þórðarson (born 1998), Icelandic professional football player Sturla Þórðarson (1214–1284), Icelandic chieftain and writer of sagas Teitur Thordarson (born 1952), Icelandic football coach Þórbergur Þórðarson (1889–1974), Icelandic author and Esperantist