Kryptonite

Batman armed with Kryptonite brass knuckles.

Kryptonite are debris from Krypton that became irradiated when the planet exploded. It’s one of the most notable weaknesses to Superman and other Kryptonians.

Origins

After Krypton exploded, the debris was irradiated. Some of it made it's way to Earth and has been used by various individuals.

Known effects

Kryptonite works instantaneously when in the presence of a superpowered Kryptonian. Exposure results in excruciating pain, along with loss of their powers and prolonged exposure is lethal. Kryptonite could also be turned into a liquid and injected into a Kryptonian to negate their powers.

Aside from this, Kryptonite doesn't have any immediate effects on humans, but prolonged exposure to humans will cause them to get ill, such as from cancer, etc.

The energy the kryptonite emits is near infinite and some people, including Lex Luthor utilize the energy from it to benefit his work. The only real defense against the material is to encase it in lead, which keeps the radiation from harming a Kryptonian further.

Known users

• Lex Luthor: When fighting Doomsday, Lex used a battle suit equipped with a Kryptonite laser cannon.
• Batman: The Dark Knight used Kryptonite brass knuckles on Superman when he was controlled by Poison Ivy.
• Harley Quinn: She used two Kryptonite blasters when fighting the Paradooms at LexCorp Tower.
• Captain Boomerang: When fighting against the Paradooms, he was given Kryptonite infused boomerangs.
• King Shark: He used Kryptonite spray on his teeth, giving his Kryptonite teeth he used to fight the Paradooms.
• Bane: He used Kryptonite Brass Knuckles to fight against to Paradooms at LexCorp Tower.
• Black Manta: He was given Kryptonite arm blades to use against the Paradooms.
• Darkseid: It’s unknown how he obtained it, but he injected Liquid Kryptonite into Superman to keep him from using his power.