Henri was a tuxedo cat, who appeared on a series of short movies. He apparently died of multiple organ failure, at the age of 17.
He was one of the early cat figures, predating many meme cats.
I am not going to pretend, this is actually the first time I ever see and hear about this cat, but I did some research and it turns out that he was indeed a famous celebrity on the Internet, actually one of the greatest cat celebrities of all time. Having lived to reach the honourable old age of 17 years means he had a long life, passed away as a dignified old gentleman and surely had experienced a lot of the sweet things that our world has to offer. However, it is still sad news and 17 years of age, while being definitely senior, is still way less than the maximum potential of cat's lifespan.
May the old Henri rest in peace.