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.
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.
And the concept is still alive and well. My kids each got a Bitzee for Christmas which is basically the same thing.
I can attest to them still existing, I collect them :) they're far more popular in Japan but in the states they limp along on nostalgia with re-issues of the older models and the occasional localisation of japanese ones
Hobbycraft in the local retail park has them by the tills. Definitely still around.