"Some days," began the tweet, "are grumpier than others." And today is one of those days. Grumpy Cat, the Internet's most famous feline, has passed away at age 7, her official Twitter account ...

In Loving Memory of Grumpy Cat: ... Grumpy Cat, the Internet's most famous feline, has passed away at age 7, her official Twitter account wrote to its 1.5 million followers today.