An often-forgotten relic from Superman's past, Superboy aired during the '80s and early '90s in syndication and it was actually quite popular at the time. Unfortunately, it hasn't aged well (which is pretty unfortunate when you take into account that it's one of the younger shows based on the Man of Steel).
The show focused on a young Clark Kent when he was just starting out his heroics. He wasn't yet Superman, so he went by Superboy instead. And strangely enough, Superboy was played by two actors, as John Haymes Newton was replaced after just one season with Gerard Christopher - who would go on to play the role for the show's remaining three seasons.
Superboy is an odd one to look back on. Its production values weren't very good but they were definitely on to something with the concept. After all, Superman's early days is exactly what inspired Smallville just over a decade later, and that show was ultimately able to do far more with the concept. That said, there is a nostalgic charm to Superboy. It's a product of its time that tried something at a time when not much was happening with superheroes, and it was mostly successful.
It started rough but when it began to embrace its comic book roots, it got infinitely better, with some solid episodes. Superboy was basically young Superman, and the show was at its best when it realized that.