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Black Kryptonite.

"It can separate the beast from the man." – Clark Kent to Chloe about the hideous Doomsday creature on the loose. Doomsday

Black Kryptonite is a form of refined Kryptonite that can separate the personalities of a single being into two separate beings. This Kryptonite is created by heating Green Kryptonite to extremely high temperatures.

Known Uses

Jor-El uses the purple radiation from Black Kryptonite to unleash his true Kryptonian side.

Black Kryptonite has been used to split several beings into different beings: one good and one evil, one light and one dark, one free and one controlled, one tame and one ferocious, one human and one monster.

  • Jor-El used Black Kryptonite on Clark to separate his Kryptonian nature from his human side.
  • Martha Kent used it to split "Kal-El", who was being controlled by Jor-El, into Clark Kent (the real Kal-El aka Superman), and his possessed Kryptonian persona. Clark stabbed "Kal-El" with Black Kryptonite. The two entities appeared to combine into a single being; it's unclear if "Kal-El" was killed, or if Clark now controlled the re-combined being.
  • Lex Luthor was split by an accident with a Black Kryptonite into a good Lex and an evil Lex. Clark used his heat vision to turn the evil Lex's Green Kryptonite ring into Black Kryptonite, combining the half-light and half-dark Lexes back together.
  • Chloe Sullivan used Black Kryptonite to divide the transforming Davis Bloome into a humanoid Davis and his rampaging monster counterpart, Doomsday. The two sides of Davis's personality were never re-combined; Doomsday was eventually buried down a geothermal facility and Davis Bloome was killed by a dying Jimmy Olsen.

Powers and Abilities

Black Kryptonite making effect.

The full potential of Black Kryptonite is unknown, but it gives off purple radiation and it seems to have the ability to literally separate personalities of humans and Kryptonians, including the genetic fusion of the monster Doomsday and the humanoid Davis Bloome.

Good personalities of Kryptonians and metahumans seemed to be less powerful than the evil ones, although this might simply be due to the lack of restraint. Kal-El showed this when he overpowered Clark Kent. It is unknown if their good personalities still had their powers or not.

It seems Black Kryptonite affects Kryptonians in any state; yet to affect a human, it must be freshly heated, as Lex Luthor was separated into two beings by heated Black Kryptonite immediately after it reached critical temperature, while, in contrast, Martha Kent, Chloe Sullivan, Bart Allen and Oliver Queen were unaffected at room temperature.

Lex is exposed to a Black Kryptonite and split in two.

Although Black Kryptonite can separate the personalities of a human person into separate bodies, it is not known what happens to the second personality if its counterpart dies. However, one body can sustain injuries while the counterpart remains unaffected, which suggests that the death of one personality would not cause the death of another. Also, Kryptonians can survive if separated and one of the personalities is killed, as evidenced when Clark Kent seemingly "killed" his Kal-El personality by stabbing him with Black Kryptonite (Although it should be noted that the two were still 'joined' at the waist rather than existing as completely physically separated). ("Crusade")

Season Three

Clark is reborn into his Kryptonian self Kal-El in a pool of Black Kryptonite created by Jor-El to fulfill his destiny and rule the world with strength.

Season Four

Martha holds a Black Kryptonite to Clark.

Black Kryptonite was discovered and/or manufactured by Dr. Virgil Swann, who gave it to his associate Dr. Bridgette Crosby who, in turn, gave it to Martha Kent to help her after Clark Kent was re-programmed as Kal-El by Jor-El in an attempt to force him to fulfill his destiny.

Lex Luthor accidentally creates a Black Kryptonite.

Martha used a piece of Black Kryptonite to separate Kal-El from Clark's soul. In the subsequent confrontation, Clark destroyed Kal-El with the Black Kryptonite, fully regaining his body. When placed near Clark's possessed body, Black Kryptonite shone a very bright electrical blue.

Black Kryptonite merged the two versions of Lex back into one.

Lex Luthor accidentally created Black Kryptonite from Green Kryptonite during an experiment by heating it to a very high temperature using a laser. This caused an explosion, and the stone separated Lex into two different entities: One was the good Lex, but the other his evil side Alexander, who imprisoned Lex and, having discovered Clark's secret, attempted to blackmail him into helping him conquer Earth by use of a Kryptonite ring and threatening to kill Lana Lang.

Fortunately, Clark was able to turn Alexander's Green Kryptonite ring into Black Kryptonite ring using heat vision. The resultant Black Kryptonite merged the two versions of Lex back into one body, with Lex apparently retaining no memory of Alexander's actions.

Season Eight

Chloe using Black Kryptonite on Davis.

Four years later, Clark asked Oliver Queen to steal some Black Kryptonite from the Luthor Mansion, as he thought Tess Mercer had some from Lex's research. Oliver, as Green Arrow, broke into the mansion, knocking out Tess's assistant and stealing the Black Kryptonite from Tess's bedroom safe using her duplicated fingerprint.

Davis and Doomsday begin to separate.

The next day, Clark met Oliver at LuthorCorp, where Clark received the Black Kryptonite from Oliver and explained that he planned on using Black Kryptonite to separate Davis Bloome from Doomsday, and sending the latter into the Phantom Zone. Clark then stored the Black Kryptonite away in his barn. When the Justice League captured both Davis and Chloe Sullivan, and Doomsday was about to emerge, Chloe used the Black Kryptonite that they took from Clark to separate the beast from Davis.



  • The effects of Black Kryptonite seem similar to the effects of synthetic Kryptonite in Superman III, where Superman was split into two personalities: a good Clark Kent, and an evil Superman.
  • A Black kryptonite was originally thought to be able to separate the "good" from the "evil" parts of human and Kryptonian personalities. However, Davis had been trying to battle his evil side for so long by murdering people in his human form that, when split by a Black Kryptonite, both parts of him turned out to be evil, as he killed Jimmy Olsen.
  • In Season 4, it was ambiguous if killing one half of someone separated by Black Kryptonite would also end the life of the surviving half. In Season 8 this was indirectly answered, as Doomsday (a being that still exists in the Superman universe) was separated with a Black Kryptonite, and the half that was mostly Davis died (Although this may have been due to Doomsday's unique nature allowing him to 'evolve' beyond the point where he 'needed' Davis rather than a definite example of a Black Kryptonite's effects).
  • In the Arrowverse show Supergirl, Black Kryptonite is used to give people extraordinary powers and create the “Worldkillers”.
  • In Witness, Eric Marsh and his gang heated up Green Kryptonite in a blast furnance, without it turning into Black Kryptonite. The only things shown to be hot enough to make the change are Heat Vision and LuthorCorp lasers.

In the Comics

  • A Black Kryptonite made its official debut into the DC Universe in September 2005's Supergirl #2, where it apparently possessed the ability to split a person or a person's personality into two separate entities. In Supergirl #3, Lex Luthor used a Black Kryptonite on Supergirl, which caused her to split into two separate people, one wearing Supergirl's traditional costume, and another wearing a black-and-white version. Her black-and-white costume is similar to the one that Superman was wearing when he returned from the dead. Luthor noted that he was given the Black Kryptonite by the New God Darkseid, who may have been responsible for its creation.

See also

Kryptonite in Smallville
Types Natural: GreenRedBlueGold kryptonite • Processed: BlackSilverGemstoneClear kryptonite
Effects Meteor infectionPsychosisMeteor freaks
Objects BulletCageHandcuffsHeartKeyRingNecklaceVictory ring
Other KryptonMeteor showers (1989, 2005) • Lead (box) • Appearances of Green K (usages)