翼善冠yi-shan-guan, a type of hat in Chinese hanfu for ancient emperors and kings.
The term first appeared in Tang Dynasty and invented by Emperor Taizong of Tang. Quotes according to the official records of Tang, Song and Ming Dynasty. “唐贞观中,太宗采古制为翼善冠,自服之。朔望视朝,以常服及帛练裙襦通着之。若服袴褶,又与平巾帻通用。见宋王溥《唐会要.舆服上》﹑《旧唐书.舆服志》。明永乐三年,定皇帝常服冠以乌纱覆之,折角向上,亦名翼善冠。见《明史.舆服志二》。”
The yishanguan also has a corresponding hat of very similar shape in the official class and the commoner class, called wushamao乌纱帽, and in fact the yishanguan can be considered a variant of wushamao.
Actually yishanguan does have another name, called wu-sha-zhe-shang-jin乌纱折上巾, which means a hat made of black gauze with folded wings upward, and that's what distinguishes it from an ordinary wushamao.
As for the origin of wushamao, it is futou幞头 in the Tang Dynasty. Futou in the Tang Dynasty originates from fujin幅巾 in the Han Dynasty. In the Han Dynasty, people wrapped their heads in a whole pair of soft cloth, so it was called fujin幅巾(It literally means a whole piece of cloth).
Some wushamao without wings, worn by officials, are similar in shape to the Yishanguan worn by the emperor. In Chinese historical dramas and costume dramas, jin-yi-wei锦衣卫, the imperial guards of secret service agent in the emperor's court often wore this kind of wushamao without wings. And most wushamao have flush, long oval wings. There is a type of wushamao with particularly slender wings that is inherited from the Song Dynasty and is considered more formal.
The pictures below are ancient wushamao from the museums' collection, as well as portraits of Ming Dynasty officials.
Because jinyiwei锦衣卫 resembles ancient agents, it is very popular among Chinese artists, who often draw characters wearing jinyiwei-style hanfu.
Then again, the following pictures are of Ming emperors wearing yishanguan. These pictures are accurate for reference.
Animated version drawn by 燕王WF
There are some ancient paintings from the Song and Ming dynasties, on which people are wearing various kinds of wushamao.
The above is the brief introduction about yishanguan and wushamao, after that I will also introduce more other types of hanfu hats.