Countdown to Final Crisis was a 52-issue comic book miniseries that impacted different worlds of the DC Universe.

The events depicted in Countdown to Final Crisis immediately followed the 52 storyline, which revealed that a multiverse consisting of 52 separate universes existed.Comic Vine: 52 #52

To coincide with the "countdown" gimmick, DC released Countdown in reverse numerical order, starting with #51 in May 2007 and ending with #1 in April 2008.Comic Vine: Countdown to Final Crisis The final issue of the series, DC Universe #0, summed up the Countdown events, preparing readers for the Final Crisis.Major Spoilers: A Look at DC Universe #0 (April 30, 2008)

The storyline proved to be a success for DC. Sales of Countdown to Final Crisis remained steadily high throughout the series, starting at 91,054CBGXtra.com: May 2007 Estimates of Diamond Comics Sales with the first issue and 72,688The Comics Chronicles: Estimates for Comics Sold by Diamond in April 2008 for the penultimate one.