The 1940s saw an explosion of heroes. There are very very few in the present day whose basis cannot be traced back to this era. Most of the heroes who appeared would be gone by the end if it. A flash in the pan. But the legacy they left is beyond compare.
This era I situate from the first issue of Flash Comics, the first comic devoted to super-heroes, until late 1944. My basic cut-off is the drop from 60 plus pages down to 52. Many series were cancelled at that point, and so it’s my general cut-off. The far end is the first appearance of Superboy, in Febraury 1945, an unmistakable late golden age event.
In this period the United States would finally enter World War II, and the comics would react with passion to the attack on Pearl Harbour. For a while, comics would delight in showing the easy victory over axis forces, but as the war dragged on, they would avoid it entirely.
Many of the artists and writers would wind up drafted, and leave to go fight. The quality of work in this era reflects it. In general, the early golden age is a period of wonderful ideas, with varied execution. The late golden age would see the true development of those ideas.
In this period I will have the bulk of my non-DC entries, following Quality Comics, Fawcett, and Fox, as they introduce characters that would become part of the DC Universe decades later.