Man, these JLA covers are getting crowded!
The story: "Challenge of the Untouchable Aliens!" by Gardner Fox, Mike Sekowsky, and Bernard Sachs. A group of giant aliens have landed all over the world, stealing each country's most destructive weapons. And this is bad how?
Roll Call: Superman, Batman Wonder Woman, Aquaman, Flash, Green Lantern, Martian Manhunter, Green Arrow, The Atom
Notable Moments: Another nice villain design courtesy Mike Sekowsky; I love the alien's blocky, almost abstract yet very expressive faces.
Even with the addition of the Atom, Fox finds a way to give each JLAer a little moment, and the story has a nice, gentle "twist" ending.
The letter column header changes again, to reflect their newest member:
...obviously, DC didn't ask Sekowsky to add the Atom, since it's pretty clear he was drawn on by what looks like a felt-tip pen(to say nothing of the lack of color), probably at the last minute by someone in the offices.
Thus begins a tradition that will run a few years where DC will desperately add, subtract, and re-draw stuff on this one piece to reflect the current team, regardless of how Frankentsein-y it starts to look.