Mammút is an Icelandic rock band based in Reykjavík. Formed in 2003 as ROK, an all-female trio highlighting vocalist Kata (Katrína Kata Mogensen, daughter of former Kukl bassist Birgir Mogensen), the group expanded in early 2004 to a 5-piece band by recruiting guitarist Arnar Pétursson and drummer Andri Bjartur Jakobsson, and adopted the new name Mammút.