There are many more but these are the ones that changed the most, and I was interested in. Until I saw the Simpsons one randomly pop up on my YouTube home screen, I was not aware people were hacking Mario Kart like this and it was sort of a rabbit hole for a few hours.

People are doing it with Super Mario 64 as well - one adds Link and changes things around a bit for the Zelda franchise for instance. Quite amazing what fans are doing now.