Grumpy Cat memes, merchandise brighten up the darkest days with frowns

VIDEO: Internet Sensation Grumpy Cat Dead at 7

The grumpiest animal on the internet was a viral sensation, bringing smiles with her frown.

Grumpy Cat died Tuesday after she developed a urinary tract infection. Grumpy Cat was 7 years old. Her owners announced the news on social media, saying some days are grumpier than others.

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'Grumpy Cat' on the field before the MLB opening day game between the Colorado Rockies and the Arizona Diamondbacks at Chase Field on April 4, 2016, in Phoenix, Arizona.

Credit: Christian Petersen/Getty Images

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Credit: Christian Petersen/Getty Images