Guðmundur Steinn Gunnarsson (born 1982) is an Icelandic composer, performer and a founding member of S.L.Á.T.U.R., an experimental arts organization in Reykjavík.

[1] He also attended Karlheinz Stockhausen’s courses in Kürten in 2004,[3] went to the Darmstädter Ferienkurse in 2008[5] and has had masterclasses with Helmut Lachenmann, Tristan Murail, Pauline Oliveros and Clarence Barlow.

[10] Guðmundur Steinn's musical style combines sound patterns without using a rigid rhythmic grid structure or pulse.

[2] As Guðmundur Steinn explains, "By intently focusing on small differences, both in rhythm and pitch, the ear gets tuned to a microscopic mode of listening.

[1] Guðmundur Steinn also participates in improvisatory performances, and has performed with Steve Hubback, Fred Frith, Andrew D'Angelo, Ad Peijnenburg, Hilmar Jensson and Skúli Sverrisson[4] Guðmundur Steinn is a founding member of the S.L.Á.T.U.R.