>>149748306
Hank Henshaw was a one-off villain in Superman that was created by Dan Jurgans. Basically a tragic version of the FF who's powers were killing them/made them freaks, so much so that Not-Thing and Not-Human Torch KILLED THEMSELVES rather than live after they got their powers that made them freakish monsters. Hank (the Reed stand-in) heroically sacrificed himself to save his wife from fading out of existence from her powers, but the experience and watching her brother/friends kill themselves drove her insane with survivor's guilt. When Jurgans brought Hank back several issues later as a digital ghost, his wife killed herself and Superman was forced to put Hank's digital ghost self into the ship that brought him to Earth and send it into outer space as Hank's reaction to his wife's suicide was to basically threaten to crash all electronic equipment on Earth.
Hank's return as a mega villain was always planned but Jurgans incorporated his return as part of Reign of Supermen when they had to kill off Superman after the Lois and Clark wedding got delayed due to the TV show. Hank could now manipulate/reshape technology and Superman's ship had his DNA in it, so he created a device that birthed a half-machine/half-superman new body which he used to pretend to be the dead Superman so he could wipe out all life on Earth turning it into a new Warworld with Mongul's help. With the first city to be destroyed to create an engine for Warworld being Coast City, Hal Jordan's hometown and it's destruction led to Hal going crazy and becoming Parallax/destroying the Green Lantern Corps.
As for why people like Hank, besides the cool visual look he has, he's basically a really well done well made edgelord villain and I'd make the case he's not Superman's Black Manta but his Joker. Hank Henshaw DOES kill and DOES make good on his pledge to kill, meaning that Superman is dealing with a legit psychopath with all of his powers.