1. When Fry's Dog Seymour Waits for Him... And Uncontrollable Sadness Ensues
Season 5 Episode 2: "Jurassic Bark"
This is the episode that can make a grown man cry. I have witnessed this personally. It will probably go down in history as one of the saddest moments in television history, and it involves an animated man and his dog. Fry and Bender go to a museum where the pizza place that Fry worked at has been unearthed and reconstructed. He finds the focalized remains of his old pet and "best friend" Seymour. He brings it back to the Professor who tells him he can clone and restore him to life from a fossil. Bender is jealous of the fossilized dog and even throws him into a lava pit so Fry would pay attention to him. Fry is mad at Bender, but gets over it as usual. He recover Seymour from the lava and after learning the dog went on to live for over a decade after he was frozen, Fry thought he wouldn't remember him anyway. Warning, this is where the sad part comes. It cuts to a montage of Seymour obeying Fry's last command to wait for him in front of Panucci's Pizza. The song "I Will Wait for You" plays over the season's changing, and years passing until Seymour finally passes away waiting for his master to return. It is literally the saddest thing I have ever watched and every time the episode comes on I have to immediately turn it off.