The sun.

The Sun, no not the newspaper of the same name but the star we see in the sky. Around 4.5 billion years old it's about half way through it's life. That's bad news for us here on planet earth, you see in about another 5 billion years the sun will become a red giant, and that's going to expand it over us destroying all life on earth (assuming there's any left by then anyway) So in a few billion years it'll be time to start looking for new real estate somewhere else, or investing in some fireproof clothes for everybody.