Marmais (Bulgarian: Мармаис) (died 924) was a Bulgarian military commander, noble and komita (duke) of a western Bulgarian region (Sredets or Macedonia) during the reign of Emperor Simeon I (893–927). He was a descendant of an ancient Bulgarian family. He participated actively in the Byzantine-Bulgarian Wars but he is better known for his interference and campaigns against the Serb principality of Raška.
In 917 the Serb prince Petar Gojniković, who was an ally of the Bulgarian Emperor openly changed sides and supported the Byzantines. This danger from the rear played a significant role for the delay of the advance towards Constantinople after the striking victory at Anchialus. In the fall of that year Simeon sent a punitive expedition force against the Serbs, led by Theodore Sigritsa and Marmais. They convinced Petar Gojniković to meet them, captured him and sent him to Preslav. They pointed Peter's cousin Pavle Branović for the next ruler of Raška but three years later he also betrayed his alliance with Bulgaria. Marmais changed him with Zaharije Pribisavljević but he also started hostile actions against Bulgaria in 924. Marmais and Sigritsa lead a small army against him but they were ambushed and defeated, and their heads were later sent to the Byzantines.
The death of Marmais caused a major campaign against the Serb principality which was totally defeated and turned into Bulgarian province in the same 924.