Get Fuzzy and Doonesbury: Boogie shark.

Most great comic strips are built on great characters. And having great characters lets artists do things they ordinarily couldn't do.

Neither of these strips has a traditional joke. The pun in Get Fuzzy is buried in the middle panels and never explicitly commented on, while the construction of the joke in Doonesbury is so fractured that it doesn't really play as one. Both artists even go so far as to make little meta-jokes about the subtlety of the jokes that would normally be the centerpiece of a comic by having characters not get them.

But both strips are funny anyway, entirely because of the character interaction. Comics with lesser characters can't get away with this particular kind of subversion and still be funny.