Rapala cassidyi, the Cassidy's flash is a lycaenid butterfly found in Sulawesi.

[1] It was discovered in 1985 during the Project Wallace expedition of the Royal Entomological Society.

[1] The species lives in northern Sulawesi, Indonesia, in Bogani Nani Wartabone National Park.

The upperside of the male is unusual in that it has only a small amount of pale orange on the discal area of the forewing below the cell; a pattern more reminiscent of females of the genus.

The underside ground colour is light slate brown with a glossy sheen.