Old Yeller or Where the Red Fern Grows, can't remember which one I saw first, but I know that I cried for both. Probably still would if I watched them again. I'm a sucker for dogs.
ETA: Futuruama's 'Jurassic Bark' was mentioned. frick me, I change the channel whenever that comes on. I'm too big of a pussy to not cry at the ending.
This post was edited on 1/18 at 6:53 pm