In the world of DC Comics, "The Flash #21" has been the title of several major turning points across different eras. Whether you’re looking at the iconic "The Button" crossover or the first meeting between two generations of speedsters, these issues are legendary for redefining what it means to be the Fastest Man Alive. The Button: A Collision of Worlds
: Believing Kid Flash might be linked to a series of Speed Force murders, Barry chases the bratty teen across the globe. Flash 21
: In this timeline, Wally West has become a "war general," sending speedster copies of himself on suicide missions to defeat the villain Eclipso. In the world of DC Comics, "The Flash
In more recent stories (2025), The Flash #21 has explored even weirder cosmic horror. : In this timeline, Wally West has become
: Barry Allen and Bruce Wayne team up to investigate a blood-stained smiley face button found in the Batcave.
One of the most famous versions of The Flash #21 was published in 2017 as the second part of " The Button ". This storyline directly connected the world of the Flash to the mysterious Watchmen universe.
In the 2013 New 52 continuity, The Flash #21 gave fans a long-awaited "race of the century" between Barry Allen and the impulsive teenager Bart Allen, also known as Kid Flash.