Icelandic actor, comedian and screenwriter, best known as a member of the comedy group Spaugstofan. Since the late 1970s he has appeared in numerous films and television series, and has also performed at the National Theatre of Iceland. He is known for his recurring characters in the television series Spaugstofan, including Ragnar Reykjas and Kristján Ólafsson.

Sigurður has appeared in many seasons of the annual television show Áramótaskaupið. He is also one of Iceland's leading voice actors and has dubbed numerous animated films. In March 2015 Sigurjónsson appeared in the music video for the song "Crystals", the lead single from Of Monsters and Men's album "Beneath the Skin".