Warning! Major spoilers for Suicide Squad: Bad Blood ahead!
In DC Comics' Suicide Squad: Bad Blood the antihero team is joined by the Shark, a classic villain who quickly proves to be much more sinister and sadistic than Suicide Squad's resident man-eater King Shark. King Shark is nowhere to be seen in the current run of Suicide Squad and has seemingly been replaced by Karshon, who was first introduced in Green Lantern #24 way back in 1963. In Bad Blood appearance, when Karshon brutally kills an international terrorist named Scale, his full violence is on display, but it is what he does to Scale's twin brother, Fin, that elevates him past King Shark's violence and puts him in the category of true evil.
Karshon, the Shark, is a mutated tiger shark that arose from deep within the ocean with a powerful aquatic body and strong psionic powers. In Suicide Squad: Bad Blood #1 the team is tasked by Amanda Waller with neutralizing an international cell of super-terrorists calling themselves The Revolutionaries. After bloodily defeating much of the terrorist cell, the Suicide Squad is shocked to learn that the surviving terrorists will be joining their squad as teammates, which clearly puts a strain on all members of the squad.
Suicide Squad: Bad Blood #1, from writer Tom Taylor and artist Bruno Redondo, sees Karshon the Shark aggressively killing the aquatic terrorist Scale, and having a good time doing so. By the end of the issue, Fin, the twin brother of Scale, is forced to join the Suicide Squad and fight alongside his brother's murderer. The tension between the two leads to a psionic showdown in which the Shark tortures Fin with visions of his brother being killed. While King Shark is known, and beloved, for his lower intellect and seemingly goofy murder sprees, it is clear that the Shark does not share King's wholesome personality, instead relying on wanton brutality and torture to get his way with both enemies and teammates.
Not only does Karshon force Fin to watch his brother's death all over again, but the Shark is seemingly gleeful when psionically sharing his experience of ending Scale's life. This is where the biggest difference between the Shark and King Shark is made clear. King Shark kills and eats people because he is a shark, whereas the Shark actively goes after heroes and villains alike to because he enjoys doing it. King Shark has some possibility at redemption, as he has been shown in the past to be able to adapt and change his murderous behavior. Karshon, on the other hand, is all business, and clearly has no interest in curbing his violent desires.
The Shark's horrifying murder of Scale, and subsequent sadistic torturing of his brother Fin, quickly come back to bite him. In Suicide Squad: Bad Blood #3 Fin betrays his "teammate" and uses his ability to telepathically control aquatic life to summon a swarm of sharks that easily overpower and devour Karshon. While the Shark will most likely not be joining in on any future Suicide Squad missions, it is clear that Karshon reigns supreme as the Squad's "most evil shark."