The world's crankiest cat, whose permanent scowl inspired countless memes, a best-selling series of books and a movie, has passed away at the age of seven.

Grumpy Cat - real name Tardar Sauce - shot to fame in 2012 in a YouTube video that received 15.7 million views, and went on to amass a $100M fortune for her former-waitress owner Tabatha Bundesen.

But her family from Morristown, Arizona, took to Instagram this morning to announce the news that she'd died on Tuesday from a urinary tract infection, saying: 'Some days are grumpier than others'.

The internet sensation was born with feline dwarfism and an underbite, which caused her famous expression.

However her condition also brought with it a number of health complications, including infections, which experts say drastically reduced her lifespan.

Heartbroken fans have rushed to pay tribute to the much-loved pet online, with one summing up the feelings of many by writing: 'We are all a bit of you.'

The internet sensation Grumpy Cat, owned by Tabatha Bundesen from Morristown, Arizona has died, aged seven

Within days of her cat's first appearance on social media, Grumpy's owner Tabby Bundesen was able to quit her job as a waitress. She has earned a reported $100M from her famous pet

Grumpy Cats disgruntled face won her worldwide fame when Tabatha's brother uploaded images to the r/pics sub-Reddit (pictured above) and soon became the subject of countless internet memes

A statement released by Grumpy Cat's owners read: ‘We are unimaginably heartbroken to announce the loss of our beloved Grumpy Cat.

‘Despite care from top professionals, as well as from her very loving family, Grumpy encountered complications from a recent urinary tract infection that unfortunately became too tough for her to overcome.

‘She passed away peacefully on the morning of Tuesday, May 14, at home in the arms of her mommy, Tabatha.

‘Besides being our baby and a cherished member of the family, Grumpy Cat has helped millions of people smile all around the world – even when times were tough.’ ‘Her spirit will continue to live on through her fans everywhere.’

Game of moans! A very unimpressed Grumpy Cat posing for a selfie with GoT star Peter Dinklage

Hollywood debut, Grumpy Cat's Worst Christmas Ever, attracted millions of viewers. Pictured: The famous feline at Nickelodeon's 28th Annual Kids Choice Awards in March 2015

Grumpy Cat's family announced that she'd died from a urinary tract infection, despite care from top professionals

Why did Grumpy Cat look so grumpy? Grumpy Cat suffered from feline dwarfism – a condition caused by genetic anomalies which lead to stunted growth and abnormal body proportions. Her famous expression is caused by a combination of a severe underbite and an underdeveloped jaw. Dwarfism in cats carries a number of other side-effects, including a series of health issues such as heart and lung problems, mobility issues and neurological complications. In its most extreme form, cats with feline dwarfism are sometimes referred to as perma-kittens as those suffering retain kitten-like features for the entirety of their lives. Grumpy Cat and fellow viral feline sensation Lil Bub are both considered perma-kittens and credited for helping to raise awareness of the serious disorder. According to Dr. Nicola Painter of the Manhattan Cat Specialists, feline dwarfism can drastically reduce a cat’s life expectancy. Grumpy’s tender age of seven is considered ‘an average life span for a cat with dwarfism.’ Advertisement

Grumpy Cat became an instant online sensation in September 2012, when Tabatha’s brother Bryan uploaded photos showing off the cat's now iconic scowl to the sub-Reddit r/pics.

Reddit users responded in their thousands, instantly creating Photoshopped images of Grumpy and sharing amusing memes of her on other platforms such as Twitter and Facebook.

An image uploaded to Imgur reached a staggering 1,030,000 views in its first 48 hours on the site.

In response to the interest in her unusual looking feline, Tabatha uploaded a video of Tardar Sauce to YouTube to prove her face hadn’t been Photoshopped.

Racking up more millions of views, the legend of Grumpy Cat was officially born.

Owner Tabatha then quit her job as a waitress at Red Lobster to manage Grumpy's career and said the phone 'never stopped ringing' from then on in.

Grumpy’s first taste of super-stardom came during her participation at the 2013 South by Southwest Interactive festival in Austin, Texas.

Attendees stood in line for hours hoping to take a selfie with her, but even the fanfare wasn’t enough to turn Grumpy’s frown upside down.

Yet despite her dissatisfied appearance, Tabatha says Grumpy Cat was actually very happy, regularly playing with balls of string or cuddling up to family members on the couch.

Fans have rushed to social media to pay tribute to the famous pet that became a social media sensation

Friends in high places! Grumpy Cat backstage with Jennifer Lopez at American Idol in April 2014

At the time of her death she had 2.4m followers on Instagram, 1.5m followers on Twitter and 8.5m likes on Facebook.

In the two years after her first photograph was posted to Reddit, it's believed Tabatha amassed in excess of $100,000,000 from Grumpy Cat's paid appearances, book deals and modelling shoots - more than Hollywood stars Nicole Kidman, Cameron Diaz and Matthew McConaughey.

In a 2014 interview with the Huffington Post, Tabatha insisted the number wasn't strictly accurate but refused to speculate whether it was too high or too low.

Grumpy was also the 'spokescat' for a Friskies brand of cat food and appeared on a number of TV Shows, including Good Morning America and American Idol.

She even had her own online merchandise store and a brand of iced coffee, Grumppuccino, produced by US coffee company Grenade.

But in 2018, Grumpy Cat Limited sued Grenade for exceeding the terms of an agreement made over use of the cat's image, after it started selling other branded products featuring her face.

Grumpy's owners ultimately won a $710,000 (£555,000) payout in a copyright lawsuit.

Her first book, Grumpy Cat: A Grumpy Book, was published in 2013 and acted as a guide for 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 equally as amusing follow-up, The Grumpy Guide To Life: Observations By Grumpy Cat, ranked third on the New York Times How-to Bestsellers list, advising readers that 'It's always good to have a partner in crime - you need someone to blame when people start asking questions'.

Her Hollywood debut, Grumpy Cat's Worst Christmas Ever, attracted 1.7 million viewers on its November 29, 2014 release date and became the most tweeted about event that day.

Voice by Parks and Recreation star Aubrey Plaza, Grumpy played a lonely and discarded cat living in a pet store who finds friendship with an equally lonely 12-year-old girl.

The movie was largely panned by critics but it didn't stop Grumpy's fans from enjoying seeing the four-legged star transition from the computer screen to the big time.

The famous feline even had her own waxwork made at Madame Tussauds in San Francisco after the film, which was unveiled in 2015.

Tabatha credits Grumpy Cat for completely changing her life and the rest of her family's too.

'[I'd] been waitressing for 10 years, barely making ends meet,' she said in a 2014 interview.

'Now I get to travel with the cat, and I’m homeschooling Crystal, so we get to spend more time together. I hardly ever saw my brother before all this happened, maybe once or twice in 10 years, and now I get to see him every couple months at least.

'It's a huge positive change. Plus, there's the joy that Grumpy Cat is spreading—or grumpiness. But really, everybody’s smiling.'

Johnny Knoxville made sure to put on his best pout for his encounter with Grumpy Cat

Chat show guest! TV host Conan O'Brien also had a cuddle with the famous feline

Grumpy Cat suffered from feline dwarfism – a condition caused by genetic anomalies which lead to stunted growth and abnormal body proportions.

Her famous expression is caused by a combination of a severe underbite and an underdeveloped jaw.

Dwarfism in cats carries a number of other side-effects, including stunted growth, thick-looking joints, a curved spine and bow-legged posture.

With the condition also comes a series of health issues such as heart and lung problems, mobility issues and neurological complications.

In its most extreme form, cats with feline dwarfism are sometimes referred to as perma-kittens as those suffering retain kitten-like features for the entirety of their lives.

Grumpy Cat and fellow viral feline sensation Lil Bub are both considered perma-kittens and credited for helping to raise awareness of the serious disorder.

Grumpy’s brother Pokey - who was born in the same litter of four as her - also suffers from the condition and is said to have ‘a flat face, bubble eyes and a short tail’, though he didn’t inherit his sister’s perpetual grimace.

Practicing their scowls! Famous feline Grumpy Cat with Walking Dead star Andrew Lincoln in New York in October 2015

Inspiration for a new character? The late Stan Lee - who co-created heroes such as Spider-Man for Marvel Comics - posed with the famous pet in November 2015

According to Dr. Nicola Painter of the Manhattan Cat Specialists, feline dwarfism can drastically reduce a cat’s life expectancy, and Grumpy’s tender age of seven is considered ‘about an average life span for a cat with dwarfism.’

‘It’s likely that Grumpy Cat had to be euthanized during the final stages of her urinary tract infection (UTI), and subsequent kidney infection,’ Painter said to DailyMail.com.

‘It’s not unusual for dwarf cats to pass suddenly. Even in regular cats, for kidney infections we give 50/50 odds of survival because it’s notoriously difficult to treat.’

Painter added that with UTI’s, often there are no or very minor symptoms before the cat suddenly falls very ill.

‘Feline dwarfism doesn’t directly affect a cat’s immune system, but bone and cartilage growth – which is impacted by the condition – is linked to kidney development.

'This means Grumpy was likely more susceptible to infection than other cats, because he kidney were probably underdeveloped.

‘It seems Grumpy Cat received the best care possible and was very well looked after, but unfortunately there are so many medical complications with feline dwarfism, sufferers just don’t live as long.’

Tabby Bundesen cuddles up to Grumpy Cat, mimicking his famed expression on June 17, 2014

Grumpy Cat - real name Tardar Sauce - was born with dwarfism and an underbite, giving her a disgruntled expression

Screen star! Grumpy made her Hollywood debut in November 2014 in Grumpy Cat's Worst Christmas Ever (pictured)

Grumpy's real name, Tadar Sauce, was chosen by Tabatha's daughter Crystal who believed the cat's white and grey coloring resembled a pot tartar sauce.

Crystal had recently tasted the condiment at the restaurant where her mother worked, and Tabatha believes tartar sauce was 'fresh in her mind when the kitten was born.'

The difference in spelling is also credited to Crystal, who misspelled 'tartar' when suggesting the name to Tabatha.

She was a mixed-breed cat, but her family say her exact lineage isn't known.

Her mother is a calico short hair domestic cat and her believed father had grey and white stripes.

'Though I suppose there could be a different father, promiscuous cats you know...' her family theorized on Grumpy's website.

Tabatha says Grumpy looks nothing like her mother of father, and instead believes she may have been a mixture of calico and Persian, Ragdoll, or Snowshoe.