Gustaf Grefberg (born February 18, 1974) is a Swedish musician. As part of the Amiga scene, he is known under the artist name Lizardking, and much of his production is tracker music. He is or has been a member of the demo groups Alcatraz, The Silents, Razor 1911, The Black Lotus & Triton. He and Joakim Falk invented a musical style called "Doskpop" and he released various music disks such as "Doskpop The Compilation" or "Memorial Songs 1+2" which feature many tracks in this style. He also took part in projects such as Merregnon and the Symphonic Game Music Concert-series in Leipzig, Germany.
In 1994, he released a compact cassette, Mindlitter, in cooperation with Martin Wall. They were in person selling the tapes at the Assembly '94 demo party. He is a full-time composer of the Swedish company Starbreeze Studios, which specializes in the development of computer games. He has composed the score of several Starbreeze Studios video games, including Enclave, Payday 2 (several tracks), Justice, Knights of the Temple: Infernal Crusade, The Chronicles of Riddick: Escape from Butcher Bay, Magus Dawn, The Darkness and Brothers: A Tale of Two Sons. The soundtrack to "The Chronicles of Riddick: Escape from Butcher Bay" received the award "Best Game Soundtrack of 2004" from the leading German gaming magazine GameStar.
In the Spacesynth community, he is known by the artistic name Xain.
