Thanks to the internet, almost everybody has seen or heard of the almost forgotten animated Superman.
I was 25 when I first saw them. They started showing up on video tape collections of old (read public domain) cartoons. As a fan of animation, and the Big Blue Cheese, I couldn't get enough of them. I found out there were 17 shorts in all and set about finding them.
These short films were the template for Batman: The Animated Series, which influenced practically every cartoon, superhero or not, for the next 20 years.
If you're a fan of animation, it behooves you to study the work of The Fleischer Studios, not just Disney. It's a different feel to animation than just about anything out there. Especially in context to when they were produced. Disney went one way and the Bros. Fleischer went another. They were very much akin to Dreamworks Animation's position to Pixar today.
Below is one of my favourite episodes of Superman, Terror on the Midway. It's moody, stylish and a little creepy. I plays with the medium like Disney never did. The typical Superman hokum is at its bare minimum and a real sense of peril permeates every frame.
Also check out the gallery of layouts and production art via Ryan and Stephanie's Fleischer Art Collection.