Sigurjón Þórðarson (born June 29, 1964) is an Icelandic politician. He was a member of the Althing for the Liberal Party from 2003 to 2007. In 2010, he was elected leader of the Liberal Party. In the municipal elections in May 2010, Sigurjón was elected to the municipal council of Skagafjörður.
Sigurjón has a BS degree in biology from the University of Iceland and studied water pollution control technology at Cranfield University. Sigurjón is a pagan priest.