Grumpy Cat in an undated photo provided by Nestle Purina PetCare. AP/Nestle Purina PetCare With a relentless look of malevolence, Grumpy Cat is not exactly cute.

But the piercing stare and air of withering contempt have proved astonishingly lucrative for the cat’s owner, Tabatha Bundesen of Morristown, Arizona.

In just two years the cat — whose real name is Tardar Sauce — has made $99.5 million from an array of products, including best-selling books and a film.

Not surprisingly, Bundesen believes her pet 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's earnings have dwarfed those of many of Hollywood's biggest names, such as Gwyneth Paltrow who, according to Forbes magazine, earned just over $18.6 million last year.

The cat is also outstripping the world’s top footballers including Christiano Ronaldo, whose total remuneration this year is estimated at $42.2 million.

Grumpy's permanent scowl is a result of her having been born with dwarfism and an underbite.

She became an internet superstar after Bundesen's brother posted a picture online.

Her fame spread rapidly especially once she was taken up by Ben Lashes — an "internet cat" agent.

The frown has proved irresistible on social media for 521,000 followers on Instagram and 255,000 on Twitter.

There have been a line of products including a brand of iced coffee, called Grumppuccino, and the cat is also "the face" of Friskies.

Last year the curmudgeonly cat appeared on the front pages of The Wall Street Journal and New York Magazine.

Grumpy’s big-screen debut is coming soon. The film "Grumpy Cat’s Worst Christmas Ever" has been billed as a cross between "Home Alone" and "Die Hard. "

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