Carolus Rex is the sixth studio album by the Swedish power metal band Sabaton. It is a concept album based on the rise and fall of the Swedish Empire, whose monarch Charles XII gives it its title. It was released with both English and Swedish vocals. It is the last album to feature guitarists Oskar Montelius and Rikard Sundén, drummer Daniel Mullback and keyboardist Daniel Mÿhr. It was produced by Peter Tägtgren in Abyss Studios. The album received critical acclaim and commercial success, achieving gold certification in Poland and quadruple platinum in Sweden.