Dc Comics Presents No. 49: Superman and Shazam!

The first appearence of the Kryptonite!!! Superman's deadly weakness

 We all know that Superman's main weakness is the mineral known as kryptonite, which comes from his home planet Krypton.

This is the first story in which the kryptonite makes an appearence but it surely won't be the last.

Superman #153 "The Town of the Supermen"

The origin of the original Green Lantern, Alan Scott

Here's the origin of the original Green Lantern, Alan Scott, created by Martin Nodell and Bill Finger and first appearing in the comic book All-American Comics #16, published in 1940.