When i was adding some Golden Age books to my project a little while back, i kept running into this guy when i was doing screenshots (i have reprints of other stories from these issues, but not this actual story, to my utmost disappointment). I half considered going out and seeing if i could get a copy of this but i have enough to review right now. But then when the turtle guy (the much less aptly named "Mzee") appeared recently among the Red Skull's new minions in Uncanny Avengers, i was really hoping he would turn out to be the same dude. Doesn't seem to be the case, but for the record...

The ad in Captain America Comics #22:

And some choice scenes from the actual story in issue #23:

Now, it turns out that he's just a guy in a turtle suit, but you've got some balls going up against Captain America with just that, and to be fair, he does have trained attack turtles.