The Yellow Scourge

Operator 5 - A really powerful secret agent dude. Fights The Yellow Empire, even though they're invisible a lot of the time. He had only just rid the world of The Purple Emperor, it was obviously a time when America was under threat from a variety of colours.
Cover by George Gross, who also did all the covers of The Avenger series.
'Operator 5 matched his individual might against a million war-drunk terrorists.'
That's quite hard.