Dr. Jerry Bailsí THE COLLECTORís GUIDE: THE FIRST HEROIC AGE (A Panelologist Publication, 1969) covers 49 publishing groups. Mr. Bails attempted to list all super-hero strips from 1934 thru 1947. I counted 601 separate entries. Some were groups (JSA, 7 Soldiers, Young Allies, etc.).
Sidekicks didnít warrant a separate entry unless they had their own feature. So, assuming one accepts those dates as the parameters of the Golden Age (and that I counted correctly), itís safe to say there were slightly north of 601 super-heroes in that time period.
I started to look at the Keltner index (1935-1955) but gave up after only two publishers. Too daunting far me! Iíll leave that up to someone made of sterner stuff and/or with younger eyes!