Calvin and Hobbes, and you never see his cartoon characters or images on novelty items (Calendars, Coffee Mugs, etc.). You can still get copies of the comic strip series which ended in 1995, and they rerun them online, but that's about it.
I came across a blog telling of Bill Watterson temporarily stepping out of reclusive retirement to ink three days of comics for Pearls Before Swine.
You can learn about it here, along with links to the three comic strips, on the blog of Pearl Before Swine's cartoonist, Stephan Pastis.
Link: Ever Wished That Calvin and Hobbes Creator Bill Watterson Would Return to the Comics Page? Well, He Just Did
I particularly liked the 2nd comic strip with the spaceships. Reminded me of Spaceman Spiff.
I miss those days.