During the event, pairs of Marvel and DC characters were merged into single characters. The same was done with teams and fictional locations. Usually the merged characters had something in common (for example, the four-member Jack Kirby creations of the Fantastic Four and Challengers of the Unknown, or water-themed heroes Namor the Sub-Mariner and Aquaman), or their names or themes allowed for clever combinations (such as Superman and Captain America's amalgamation, Super-Soldier, a reference to the Super Soldier serum that created Captain America; Bat-Thing, an amalgamation of Man-Bat and Man-Thing; or Shatterstarfire, the amalgamation of Shatterstar and Starfire).