Platyptilia williamsii (calendula plume moth) is a moth of the family Pterophoridae. It is known from western North America, including California.
The head and thorax have mixed ocherous-brown and whitish scales. The antennae are brown dotted above. The forewings are ocherous-brown with dark brown patches, with white irroration (speckling) forming a trace of transverse wavy lines and dotting the brown costa. The fringes are brownish gray with whitish bases containing brown and white scales. The hindwings and fringes are gray-brown.
The larvae feed on Calendula species, as well as Senecio aronicoides and Senecio jacobaea.