Mambrino

Mambrino was a fictional Moorish king, celebrated in the romances of chivalry. According to legend, Mambrino possessed a helmet of pure gold that rendered its wearer invulnerable. Possession of the helmet was the ambition of all the paladins of Charlemagne, and it was carried off by first by Gradasso, King of Sericane, and a second time by Rinaldo (Orlando Furioso), who slew Gradasso at Barcelona.