She is the world's crankiest cat with a permanent scowl that has inspired countless memes, a best-selling series of books and a movie.

But even the news that she has amassed a £64million fortune has not been enough to put a smile on the face of internet sensation Grumpy Cat – real name Tardar Sauce.

The feline, who shot to fame two years ago in a YouTube video that got 15.7 million views, has earned more than Hollywood stars Nicole Kidman, Cameron Diaz and Matthew McConaughey.

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Internet sensation Grumpy Cat has amassed a £64million fortune - more than a host of A-listers

Grumpy has a book deal and made her Hollywood debut last month in Grumpy Cat's Worst Christmas Ever

Owner Tabatha Bundesen from Morristown, Arizona, said the two-year-old moggy is 'unstoppable'.

She told The Express: 'What she's achieved in such a short time is unimaginable and absolutely mind-blowing.

'I was able to quit my job as a waitress within days of her first appearance on social media and the phone simply hasn't stopped ringing since.'

Grumpy was born with dwarfism and an underbite, giving her a disgruntled expression.

She is owned by Tabatha Bundesen, who lives in Phoenix, and is a regular visitor at the offices of Vogue and Lucky magazine

The two-year-old feline has inspired countless memes and has 521,000 followers on Instagram

She even made an appearance onstage at FOX's American Idol XIII and posed with Jennifer Lopez

She shot to fame two years ago in a video that got more than 15.7 million views on YouTube

Grumpy was born with dwarfism and an underbite, giving her a permanently disgruntled expression

Her first book, Grumpy Cat: A Grumpy Book, was a guide to attaining 'true grumpiness' from the self-appointed 'master of bad attitude'

She now 521,000 followers on Instagram and 255,000 on Twitter and her face appears on calendars, mugs and T-shirts.

Her first book, Grumpy Cat: A Grumpy Book, was a guide to attaining 'true grumpiness' from the self-appointed 'master of bad attitude'.

Helpful tips included eating ice cream cones to get incurable brain freezes and reminding yourself that a kiss carries more germs than 100 toilet seats.

The follow-up, The Grumpy Guide To Life: Observations By Grumpy Cat, advises that 'It's always good to have a partner in crime - you need someone to blame when people start asking questions'.

She is the 'spokescat' for a Friskies brand of cat food and her latest deal is for her own brand of iced coffee, Grumppuccino.

Her Hollywood debut, Grumpy Cat's Worst Christmas Ever, attracted millions of viewers and was the most tweeted about film on its release date.

Aubrey Plaza (right) was the voice for Grumpy in her new film and appeared on NBC News with Natalie Morales

Ms Bundesen from Morristown, Arizona, said the two-year-old mixed breed moggy is 'unstoppable'

Grumpy was born with dwarfism and an underbite, giving her a permanently disgruntled expression

Grumpy is the 'spokescat' for a Friskies brand of cat food and her latest deal is for her own brand of iced coffee, Grumppuccino

Her latest deal is for her own brand of iced coffee, Grumppuccino, which is sold in a number of stores

Her follow-up book, The Grumpy Guide To Life: Observations By Grumpy Cat, advises that 'It's always good to have a partner in crime - you need someone to blame when people start asking questions'

She has more than 255,000 followers on Twitter and her face appears on calendars, mugs and T-shirts