The internet’s most famous feline has died aged seven, its owners have confirmed.

Grumpy Cat, whose permanent scowl was the result of an underbite and feline dwarfism, was an online sensation.

Posting on social media Friday, the cat's owners in Arizona wrote that she experienced complications from a urinary tract infection and "passed away peacefully" Tuesday "in the arms of her mommy."

“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,” Grumpy’s family said in a statement.

The cat's real name was Tardar Sauce and she rose to fame after her photos were posted online in 2012.

Her sourpuss demeanour launched countless memes with an early picture captioned “I had fun once. It was awful.”

A video posted to YouTube followed, which has more than 21 million views to date.

Her fame grew to more than 2 million followers on Instagram, more than 1 million on Twitter and more than 8.5 million Facebook fans.

“Her spirit will continue to live on through her fans everywhere,” her family wrote.

Owner Tabatha Bundesen founded Grumpy Cat Limited and the cat made numerous appearances, including commercials.

Grumpy became the unhappy face of a range of merchandise, made numerous public appearances to meet her fans and even starred in a TV movie called “Grumpy Cat’s Worst Christmas Ever.”

In 2018, Bundesen won more than CA$950,000 in a copyright infringement suit against a coffee company that made Grumpy Cat Grumppuccino.

There was an outpouring of sadness at the kitty’s death on social media.

“Rest in peace Tardar Sauce AKA Grumpy Cat. This cat has brought so much joy to mine and millions of other people’s lives the last few years,” Twitter user Grace wrote.

“May she enjoy the Rainbow Bridge. Thank you to her owners for sharing her with us. I’m truly crushed by this.”

“Grumpy cat will always be a legend in my heart. RIP Grumpy Cat,” Ajeet added.

--- With files from The Associated Press