Groo is one of my favorite comics from when I was a kid. He is a warrior, unmatched in skill with the sword, who travels the land with his heroic canine sidekick, Rufferto. He is also without doubt the stupidest creature on the planet. He can't count, read, reason, or, frequently, understand things that are said to him. He appeared in several comics before a run of 120 comics in the early 90s, and has probably been in a few since, but in general Groo is no longer being done.
The comic is drawn by Sergio Aragones, whose name should be familiar to anyone who read MAD magazine over the last 20 years or so; he is responsible for the "Drawn-out dramas" which appear in the margins throughout the magazine and the occasional wordless "Tarzan" piece or some such nonsense. He has a spectacular sense of visual humor, and he is able to put a feeling of color and life into every frame of the comic, which is amazing considering the rather simple style in which he draws. There is an endless variety of townspeople and creatures populating each scene, especially the large title plates which open each comic. Despite the huge amount of people Groo kills in almost every issue, though, there is hardly a drop of blood (lots from dragons), and there is quite a light touch given to every fray.
The writing is by Mark Evanier, or so I think; he changes his title every issue. The writing is very good and each issue starts out with a little poem - nothing to run home and tell mom about, but how many other comics do verse these days? The speech has an archaic style to it, and Evanier is not too proud to alienate his younger readers by using using words like "mitigate" or referring to Groo as an "unkept wretch." Furthermore, while there is much carnage and even a little continuing story, this is not some kind of prehistoric Spider-man. Each comic is a self-contained little parable, having to do with ignorance and false beliefs (Groo and Chakaal stop an inescapable cycle of human sacrifices), environmental interdependencies (Groo introduces war, money, taxes, government, and more to an island community in perfect balance), to simple truths ("Real friends are friends to the end, and even after that"). There isn't much preaching, but it is hard to miss the messages when a society begins worshiping Rufferto, and then becomes so obsessed with the "true image" of their god that they forget what the god stood for in the first place.
If moral lessons don't flip your bit, you should read Groo anyway because of the great artwork and writing, and to see how the labyrinthine stories (they get quite convoluted as people scheme and counter-scheme) work themselves out in unexpected, simple ways - often Groo will kill everyone involved for their treachery or unconsciously instigate their total ruination. You can find Groos at any comic shop for probably a quarter each at this point.
Here's a good sample of the artwork, click it for a much larger (200k) version.