If you used to stay up late in the 90s and watch Manga on Channel 4 then you must surely remember The Legend of the Four Kings. This and the Guyver were my very first introduction to cartoons not specifically for children and I absolutely loved it. The darkness of the plots and the stylised violence are probably to blame for a lot of my neuroses, in a good way of course.
Amazingly someone has uploaded all these in fairly decent quality and put them into a playlist on Youtube! As is often the case with things I remember for being awesome but not entirely sure why - the intro music to this series brings a prodigious amount of joy. I reckon it's because on repeated listens it's got a ring of the Miami Vice Jan Hammer style of it. It's like Crockett's Theme for the 90s.
Geek Pride has an awesomely nostalgic and far better history of the 4 Later slot itself than I could justify writing. If you do nothing else, listen to the opening titles.