Þormóðssker (Thormod´s skerry) is located in Faxaflói out of Mýrar, north of Akranes in Iceland. Þormóðssker is the southernmost and westernmost skerry in a cluster of skerries. It is about 200 m long, almost 100 m wide and 11 m above sea level. The lighthouse was built on the skerry in the years 1941 – 1942, after the French marine research vessel Pourqui Pas? was caught in a violent cyclonic storm and lost on the reefs of Álftanes at Mýrar in September 1936. 23 of the crew were lost in the wreck and 17 survivors died before rescue came, leaving only one survivor.
Its name, Þormóðssker is mentioned in the Icelandic Settlement Book and there the skerry is named after Þormóð the slave of Ketil the Steam, and accordingly from the settlement period.