Lex Luthor makes his first appearance in a couple of years in these pages, as he brings forth a new villain for Superman, the Galactic Golem, in issue 248 (Feb. 72).
Although Luthor had not been in this book for a while, he had appeared in Action Comics only a couple of months before. This story, by Len Wein, Swan and Anderson, is largely told in a flashback from Luthor’s bunker, as he worries that his latest plan to kill Superman worked too well, killing everyone on Earth. Luthor harnessed cosmic energies from deep in the universe to form a creature he calls the Galactic Golem, sending it out to kill Superman.
As Luthor intended, Superman eventually becomes aware that the swirl on the creature’s forehead is his weak spot, and hits it, causing a massive destructive explosion. But when the smoke clears, there is no sign of anyone on Earth.
But that’s just because Superman figured out Luthor’s scheme, recognizing his voice as coming from the Golem, and shunted everyone into another dimension until he could dispose of the Golem, sending him out into space.
The Golem does return in a few months anyway.