Calvin and Hobbes

A control-freak author and a couple of characters out of control: what's not to love in Calvin and Hobbes? Just don't think you can sit next to me with your own book while I'm reading the strip, because I'll start chuckling and will have to interrupt to share the fun with you - even if you don't get it.

Because of Watterson's strong anti-merchandising sentiments and his reluctance to return to the spotlight, almost no legitimate Calvin and Hobbes licensed merchandise exists outside of the book collections. Some officially approved items were created for marketing purposes and are now sought by collectors. Two notable exceptions to the licensing embargo were the publication of two 16-month wall calendars and the textbook Teaching with Calvin and Hobbes.

However, the strip's immense popularity has led to the appearance of various "bootleg" items, including T-shirts, keychains, bumper stickers, and window decals, sometimes including obscene language or references contradicting or parodying the whimsical spirit of Watterson's work.
[...]
The 3,160th and final strip ran on Sunday, December 31, 1995. It depicted Calvin and Hobbes outside in freshly-fallen snow, reveling in the wonder and excitement of the winter scene. "It's a magical world, Hobbes ol' buddy!" The last panel shows Calvin and Hobbes zooming off on their sled as Calvin exclaims. "Let's go exploring!"

This is all from the Wikipedia entry.