| After the beginning of the Atomic Age and before the first modern super-heroes started to appear, there was the Monster Age. It was an age where the Earth was under assault by all manner of strange, usually giant, creatures. Some were aliens, suddenly interested in Earth for the first time now that we had mastered nuclear energy. Others were ancient creatures awoken by our nuclear tests. Others were the first mutates, created by nuclear radiation.
These stories of course weren't initially meant to be part of any "universe" (although a few have repeat appearances during this era) but later Marvel stories brought many of them into canon. Roger Stern's Monster Hunters story in the Marvel Universe book introduced the concept that some of the creatures were created or awoken by the Deviants.
The Monster Age starts earlier than, but eventually runs concurrently with, the Hero Gap, and officially ends when the FF put a stop to the Mole Man in FF #1.
I should note that, similar to the Golden Age, due to the way these issues were reprinted, with several random books put in the same reprint issue, they're not in any particular order below (except when dictated by sequel appearances), but it shouldn't matter since they're mostly all standalone stories.
|Creator notes: Stan Lee & Jack Kirby with Dick Ayers is a frequent combination. Steve Ditko is around as well. And there are many other creators that generally don't remain when the Marvel Age kicks in. As with the Golden Age, in a lot of cases, the creators are unknown.|
|New characters: Some notable monsters and other characters that we'll see again: Fin Fang Foom, It the Living Colossus, Groot, Gorilla Man, Dr. Druid, Xemnu, and the characters that will eventually become the Headmen.|