What character from The Simpsons was killed off in the year 2000?

Things that The Simpsons is older than: Daisy Ridley, the iPhone, the first PlayStation, the Soviet Union breaking up, Microsoft.com, Dollar Tree ... you get the idea.

And it's already been renewed through at least 2025. In all those seasons, only a handful of Simpsons characters have passed away. In an episode early in the year 2000, this character was one of them.

Who was it?