Who was Marvel Comics first superhero?

Who was Marvel Comics first superhero?
Photo by Waldemar Brandt / Unsplash

Today the MCU is so big that we're debating if it's worth putting out just 20 movies every year instead of like 50. It's no stretch to say that Marvel is one of the most well-known brands in the world.

But even Earth's mightiest heroes had to start somewhere. Who was the first superhero to appear in a Marvel-branded comic book?