Watership Down isn't really that sad. I mean Hazel does die in the end, but only after a long life in which he saved the warren from both men and General Wort. A satisfying end. Where the Red Fern Grows, though... that's some tear jerking shit right there.
RIP Old Dan and Little Ann.
This threads needs a photoshopped Marvin, to cheer everyone up.
See, he's smiling.
Notice the trademark lack of hair.