Monster Kirby Diablo And Blip

Monsters were coming fast and furious to the Marvel Universe, as it lacked any heroes to protect it in the pre-Iron Man and pre-Ant-Man age, but again, average humans arose to meet the challenge of the unknown...

...and, here are two more monsters that faced humanity at that time (doubling up this time, as they both only had one appearance before the Fantastic Four).

Tales Of Suspense #9 (May, 1960)

First, "I Saw Diablo! The Demon From The Fifth Dimension!" (with a little help from Stan Lee, Larry Leiber, Jack Kirby and Dick Ayers).  Diablo was a smoke demon from another dimension who came to Earth, simply looking for room (as his dimension was overcrowded).  Diablo landed in Mexico, and here, he was confronted by Ulysses Bloodstone (though this character wasn't invented until later, it was just a generic monster hunter in this issue).  Bloodstone lit a cigarette lighter and blew it out, making Diablo think humans could easily defeat him, so he went home.

Diablo seemed to have had enough of Earth.

Though all evidence shows he has not returned to Earth, Diablo was one of many aliens duplicated by Xemnu (including Goom, Taboo and our next monster) that Hulk faced in Hulk Annual #5 (November, 1976), and Bloodstone debuted in Marvel Presents #1 of July, 1975 

Tales To Astonish #15 (January, 1961)  

With this issue, "I Learned The Dread Secret Of The Blip!" as told by Stan Lee, Larry Leiber, Jack Kirby and Dick Ayers.  As Diablo was sentient smoke, Blip was living energy.  Going home from exploring another galaxy, Blip got trapped in a spacewarp and exhausted his energy getting free, and ended up on Earth to recharge.  As Blip did, he caused electrical outages for Oakville, attracting the attention of a radar operator who wasn't getting any signals.  He found Blip, learned of his story, but the pair were confronted by an angry mob.  Blip, horrified by the humans, attacked them, and then left, letting them know that their savagery convinced him not to share his secrets of the universe with humans.

Blip hoped humans would advance the next time he saw them.

There were a few other members of Blips race who encountered the Fantastic Four and the X-Men, and he too was duplicated by Xemnu, but Blip himself did return to help humanity against the Leviathons during the Monsters Unleashed 5 issue event of 2017.