Famous internet cat with millions of followers Lil Bub dies in sleep

Lil Bub, the droopy-tongued and bulbous-eyed American cat whose unusual appearance melted hearts and earned her millions of followers on social media, has died aged eight, her owner has said.

One of the internet's most beloved feline celebrities, the perma-kitten who suffered from dwarfism and battled a persistent and aggressive bone infection passed away "peacefully in her sleep" on Sunday morning.

Mike Bridavsky, the Bub's owner, announced the cat's death to millions of her followers on social media on Monday.

"BUB was cheerful and full of love laying in our bed with us Saturday night, but unexpectedly passed away peacefully in her sleep...We weren't expecting her to pass so soon or so abruptly without warning," he wrote in a post on Instagram.

Bridavsky said she helped raise more than USD 700,000 for animal charities during her lifetime.

Bub has made a huge difference in the world of animal welfare, and in the lives of millions of people worldwide, he said.

"She has literally saved thousands of lives (both pets and humans), she started the first national fund for special needs pets, she was the subject of groundbreaking genetic and biological research, she's helped raise over USD 700,000 for animals in need, and has spread a message of determination, positivity, and perseverance to people all over the world," Bridavsky said.

With millions of followers on social media and a mini-empire of commercial appearances, Bub found online fame because of her unique appearance.

Her feline dwarfism meant she stayed kitten-sized throughout her life. An extra toe on each paw, and had an underdeveloped jaw without teeth made her tongue always droopy.

Bridavsky adopted Bub as the "runt" of a ferral litter found by a friend inside a tool-shed in Indiana.

"Dearest BUB, I will never forget your generosity, your limitless supply of love, or your uncanny ability to bring so much magic and joy to the world," her owner said.

Bub's death comes seven months after the death of Grumpy Cat, another feline internet legend.