Thröstur Thórhallsson is an Icelandic chess grandmaster. He was born on May 25, 1969 in Reykjavik, and is the fourth person from Iceland to be awarded the title of International Grandmaster (IGM) by FIDE, the international chess organization.
During his early career, Thórhallsson rapidly progressed in the game, becoming an International Master in 1986 and subsequently gaining the Grandmaster title in 1996. His peak FIDE ranking to date occurred in April 2008, where he was placed 34th in the world.
Thórhallsson has taken part in multiple Chess Olympiads, representing Iceland, with his first appearance in 1986. He has also competed in several European Team Chess Championships and participated in the FIDE World Chess Championships in 1999 and 2000.
In 1998, Thórhallsson achieved one of his most notable successes by winning the Reykjavik Open, a prestigious international tournament held in his home city every year.