Flashback Friday: Black Kryptonite

Each Friday, I take one of the entries from my old Super Posts and expand it into its own featured article.

This week: Black Kryptonite!

Before we get into black Kryptonite proper, I'm not sure the conversation would be complete without mentioning synthetic kryptonite. In Superman III (1983), Gus Gorman tries to recreate Kryptonite in a lab. But since some of the chemical makeup was unknown, his concoction used tar to make up the difference, and that resulted in a new kind of Kryptonite that turned Superman "evil". Being Christopher Reeve's Superman, his "evilness" mostly resulted in growing stubble, drinking, and pulling pranks.

Black Kryptonite appears for the first time in the Smallville season 4 premiere, "Crusade" (2004). In the episode, black Kryptonite splits Clark into a good version and evil version of himself. It would go on to be used several times throughout the show, always with the same result, though often with different intentions.

Black-K made its comics debut in Supergirl #2 (August 2005), as part of a Kryptonite collection owned by Lex Luthor. It had the same effect as in Smallville, splitting Supergirl into good and evil versions. The substance was never very popular (as its use is fairly limited storytelling-wise), but it did made a few more appearances in Superman/Batman and All-Star Superman.

Despite its lack of popularity, however, it did survive the New 52. A version of it appeared on Earth -22 in Dark Knights: Metal - The Batman Who Laughs #1 (November 2017), but this version just turns the infected evil and then they die shortly afterwards. I don't know whether the difference is because of the New 52 or because it's a Dark Multiverse version or both.

But Black Kryptonite seems to be catching on in popularity because it also appeared on Supergirl last year (May 2018). Strangely, it debuted as a substance called Harun-El that was used to make the Worldkillers - the villains of that season. The Worldkillers were living as humans on Earth and their Worldkiller identities had to be awakened, after which time they worked like split personalities, so the Harun-El was eventually used to split one of the Worldkillers, Reign, from her regular persona, Samantha Arias. Later, it created a duplicate of Supergirl known as the Red Daughter, who is one of the villains of season four.