After all these years, Samurai Jack is back. You can find the first three episodes at the Adult Swim website. A little Googling will get you the rest of them. There are three episodes left to finish out the series.
It’s pretty incredible that this short, which I watched in the first half of the 2000s, comes back in 2017. In the interim the original actor who voiced Aku died, but the replacement seems rather good to me (I wouldn’t have noticed the difference).
What makes this series so special? I think it’s the seamless melange of motifs, whether from medieval Japan to a steampunk retrofuture, to science fictional time travel, combined with a stylized animation which gives one the appropriate impression of disorientation that the protagonist must be feeling when confronted with a nightmarish future.