The Phantom Zone is a plane of existence located in subspace. It is a fearsome prison used by Kryptonians to trap and imprison the most evil, malevolent and corrupted. The Phantom Zone is only accessed by the Phantom Zone Projector (designed by Thinker Guild scientist Jor-El). When a Phantom Drive is installed onto a starship (such as General Zod's Black Zero and Kal-El's infant one), it gains the ability to travel instantly to any other location in the universe by briefly passing though the Phantom Zone. However, the collision of two Phantom Drives creates a brief portal to the Zone, with it appearing as a miniature singularity, sucking into it all objects that have at one point interacted with sapphire-blue energy from the Zone.
After General Zod and his Sword of Rao loyalists staged an attempt to take over Krypton (murdering Jor-El, High Eminence Ro-Zar, and many others in the process), they were ultimately defeated and captured by the Sapphire Guards, after which High Eminence Lor-Em sentenced the war criminals to 300 cycles of "somatic reconditioning" within the Phantom Zone for the crimes of murder (of High Eminence Ro-Zar, scientist Jor-El and others) and high treason. They were each promptly frozen in cryocapsules, and sent into the huge Black Zero starship, which in turn passed into the Phantom Zone Projector, entering the Zone.
However, when Krypton exploded shortly thereafter, the Black Zero was freed from the Zone, promptly freeing Zod and his loyalists. Under the guidance of his scientist ally Jax-Ur, Zod was able to retrofit the Phantom Zone Projector into a Phantom Drive for the starship, thereby making the Black Zero a craft capable of interstellar travel, by creating portals of instant access to any remote places in space (by briefly passing through the Zone). The Sword of Rao used their newly upgraded starship to search the universe for the Kryptonian survivor Kal-El, the stolen Growth Codex, and a planet suitable to Kryptonian terraformation.
After 33 years of such travel, Zod's forces finally picked up a Kryptonian beacon and tracked it down to planet Earth, where they subsequently traveled, with the intention of terraforming the suitable planet into a New Krypton with the help of the World Engine that they had discovered on the Daxam colonial outpost.
Fortunately, the US military successfully used Superman's infant starship as a makeshift bomb against the Black Zero, with the two colliding Phantom Drives creating a temporary portal to the Phantom Zone. With Faora about to kill all aboard his C-17 cargo plane, USAF Colonel Hardy flew it directly into Black Zero, sending the plane, the Black Zero and all within reach into the Phantom Zone, with only Lois, Superman, and General Zod escaping that fate.
- Sword of Rao
- Faora-Ul - An infamous Kryptonian war criminal of the Kryptonian Civil War, General Zod's second-in-command as the Sub-Commander of the Sword of Rao. Escaped before being sent back to the Zone.
- Tor-An - A Kryptonian war criminal of the Kryptonian Civil War, operating under General Zod as his Head Pilot. Escaped before being sent back to the Zone.
- Nam-Ek - A Kryptonian warrior of the Kryptonian Civil War, operating under General Zod as his strongest soldier. Escaped before being sent back to the Zone.
- Jax-Ur - A Kryptonian leading malevolent scientist aligned with General Zod during the Kryptonian Civil War. Escaped before being sent back to the Zone.
- Nadira - A Kryptonian warrior of the Kryptonian Civil War, operating under General Zod. Escaped before being sent back to the Zone.
- Car-Vex - A Kryptonian warrior of the Kryptonian Civil War, operating under General Zod. Escaped before being sent back to the Zone.
- Commander Gor - A Kryptonian warrior of the Kryptonian Civil War, operating under General Zod. Escaped before being sent back to the Zone.
- Colonel Nathan Hardy - A human. He was a United States Air Force pilot who helped create a temporary portal on Earth, by crashing the Boeing C-17 cargo plane he was flying into Black Zero, to send the invading Kryptonians back. Tragically, his plane was sucked in as well. killing him, his crew and everyone else on board.
- Dr. Emil Hamilton - A human. He was an eminent scientist with the US Department of Defence's Defense Advanced Research Projects Agency (DARPA). He was onboard Col.Hardy's C-17, which crashed into the Black Zero. He (and everyone else on board the plane) was killed on impact.
- General Zod - An infamous Kryptonian war criminal, former General of the Kryptonian Warrior Guild and the Sword of Rao. Sentenced to the Zone for the crimes of murder (of High Eminence Ro-Zar, Jor-El, and others in the Kryptonian Civil War) and high treason against the Kryptonian Law Council. However, he would escape shortly thereafter, upon Krypton's destruction. Zod would also avoid being imprisoned in the Phantom Zone a second time during the Battle of Metropolis, as he remained out of range of the singularity created by the collision of two Phantom Drives; he battled Superman until the latter was forced to kill him.