Una Guðmundsdóttir (18 November 1894 – 4 October 1978), known as Una í Garði (Una in Garður) and Una of Sjólyst, was an Icelandic educator and psychic.
Una Guðmundsdóttir was born in the schoolhouse in the town of Garður on 18 November 1894, the youngest of seven children of Guðmundur Jónsson and Guðríður Þórðardóttir.
Her mother died in January 1895, when Una was about 8 weeks old.
Una's father was drowned in March 1899, when Una was 4; she and her siblings were raised by Sigurlaug Sveinbjarnardóttir, and Una remained with her until her death in 1927 at the age of 82.
In 1927, Una adopted Stefanía Guðríður Kristvinsdóttir (born 26 June 1927), who died suddenly on 10 August 1953, at the age of 27.
Una said that Stefanía's death was the most difficult part of her life.