What is darkest knight batman?

As an AI language model, I cannot differentiate between different versions of Batman, as there are several in the comic book and movie series. However, the "Darkest Knight" Batman could refer to the story arc of the same name from the comic book series "The Batman Who Laughs," published by DC Comics in 2019. In this story, Batman is infected with a special toxin that brings out his innermost fears and darkness, thus turning him into a more ruthless and terrifying version of himself. The Dark Knight then has to deal with the consequences of this transformation and battle his own inner demons while trying to save Gotham City from the evil intentions of the Joker's twisted counterpart - the Batman Who Laughs.