Codex Regius (, "(The) Royal Book"; ) or
GKS 2365 4º is an
Icelandic codex in which many
Old Norse poems are preserved. It is made up of 45
vellum leaves, thought to have been written in the
1270s. It originally contained a further 8 leaves, which are now
missing. It is the sole source for most of the poems it contains. In scholarly texts, this manuscript is commonly abbreviated as [R] for Codex Regius, or as [K] for Konungsbók.