Thor Vilhjalmsson (12 August 1925 - 2 March 2011) was an Icelandic writer. His first novel, Maðurinn er alltaf einn (Man is Always Alone) was published in 1950. In 1988 he won the Nordic Council Literary Prize for his novel Grámosinn glóir (Justice Undone).
Vilhjalmsson was born in Edinburgh, Scotland in 1925. He studied at the University of Iceland in 1944-1946, at the University of Nottingham in 1946-1947 and at the Sorbonne in Paris from 1947-1952. He worked as a librarian at the National Library of Iceland in 1953 and at the National Theatre 1955-1957. He was involved in many art groups and events including the Reykjavik Writers Festival, the Writer's Union of Iceland, the Federation of Icelandic Artists, the Reykjavík Arts Festival, the Reykjavík Film Festival and the Reykjavík Judo-Society.