Calonarius flavipavonius, commonly known as the yellow peacock webcap, is a species of mushroom in the family Cortinariaceae. It is rare.
The cap of Calonarius flavipavonius is brownish in color and purplish at the margins. It is convex, and sometimes becomes flat in age. It is slimy when wet and about 5-15 centimeters in diameter. The stipe is about 2.5-6.5 centimeters long and 1.1-2 centimeters wide at the top. It is whitish and can sometimes be yellowish or purplish at the top. A cortina is present. The gills are yellowish to light olive in color and are adnexed.
Calonarius flavipavonius is found under douglas fir, spruce, fir, and hemlock in coniferous forests in Western North America.