Sigrún Hjálmtýsdóttir, better known as Diddú, is an Icelandic soprano and songwriter. Educated at the Reykjavík College of Music and the Guildhall School of Music and Drama in London, she began her singing career in the 1970s as a vocalist for the popular folk and pop group Spilverk Þjóðanna. She subsequently turned to classical music, particularly Lieder and operas.
Diddú's most recent album, Hvert Örstutt Spor, was released in 2005.