The Flash #109

From 1959, this Silver Age gem features one of the Scarlet Speedster's most visually inventive villains — the Mirror Master, smirking confidently behind a massive reflective device as the Flash appears to shrink into a seemingly endless chain of smaller and smaller duplicates running into the distance. The cover by Carmine Infantino and Joe Giella captures that unsettling visual trick perfectly, with the speech bubble taunting "The Flash… going… going… gone!" promising a story full of mirror-fueled mischief. Written by John Broome, "Return of the Mirror Master!" delivers exactly the kind of imaginative Silver Age sci-fi villainy that made this era of DC comics so enduringly delightful.