After having teleported on-board the Fortress of Solitude, its members were able to invade it as it was still unable to protect itself from Time Travelers. While the members are not yet known, their field leader seems to be the same inmate who was shown jailed in the Phantom Zone (Ish #5). Thanks to his cybernetic/mechanical hand he was the only one capable of shattering the Kryptonian sunstones surrounding Superman's spaceship, thus stealing the ship's engine(powered by Kryptonite) which was the sole reason for their arrival. It was later revealed that their mysterious benefactor was in fact the same person Glen Glenmorgan was having a conversation with right before they were confronted by Superman (Ish #1).
The Anti-Superman Army was created by writer Grant Morrison and was drawn by artist Andy Kubert. Throughout the years there have been various teams, although under the name of Anti-Superman Gang, with their only purpose being to take Superman down.