A grumpy cat has left its owner smiling, after amassing a £64m fortune from its grouchy expression.

Tabatha Bundesen, of Arizona, is celebrating the unlikely windfall following the viral internet success of the critter, who now boasts his own line of products, books and even an upcoming film, ‘Grumpy Cat’s Worst Christmas Ever’.

The sulky whiskers have also graced the cover of The Wall Street Journal and New York Magazine.

Tabatha said: “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."

Sadly, despite her fame and fortune, Tardar Source remains as grumpy as ever having been born with dwarfism and an underbite – source of her peculiar characteristics.