"Holy...!" (for example "Holy shit!", "Holy mackerel!" or "Holy smoke!", and perhaps most commonly "Holy cow!") is an exclamation of surprise used mostly in English-speaking countries.
Robin of the Batman TV series is noted for his many catchphrase "Holy..." exclamations. The lines in the 1960s TV series were uttered by Robin actor Burt Ward and were directly related to the plot; for example, "Holy Graf Zeppelin!" is uttered by Robin upon seeing an aerial balloon.[1][2] In his cameo on the Arrowverse crossover "Crisis on Infinite Earths", Burt Ward exclaims, "Holy crimson skies of death!" while Earth-66 experiences red skies due to the incoming antimatter wave.[3]