I'm not sure I the Tamagotchi deserves a place on here.
Did anything really kill it? It was kind of just a fad in the late 90s and its still around, not as popular as its fad stages but still reasonably popular. We just got back from Japan last week, there is a newly opened "Tamagotchi Factory" shop which was packed. The kids each picked up one of the latest versions and have been playing with them every day.
Hobbycraft in the local retail park has them by the tills. Definitely still around.
And the concept is still alive and well. My kids each got a Bitzee for Christmas which is basically the same thing.
I saw some brand new tamagotchis in the toy alley of a supermarket while looking for a gift as recently as a few weeks ago.
People may be not crazy about it as they used to but they are definitely still a thing.