Lil Bub, one of the first cats propelled to fame via the internet, has passed away according to her caretakers.

The tiny tabby, who was afflicted with feline dwarfism and the rare bone disease osteopetrosis, first came to prominence when photos of her popped up on Tumblr and Reddit in 2011. Her human, Mike Bridavsky, built a social media presence for the little cat, sharing her daily exploits with millions of followers on platforms like Instagram and Facebook. Lil Bub’s celebrity was also used to raise money for animal welfare and homeless pets.

Bub’s unique look was a hit with online cat aficionados. Because of her conditions she remained the size of a kitten, her limbs were shorter than average, and her teeth never grew in. Most photos of the beloved cat show her tongue lolling out of her mouth and an inimitable facial expression that looked like a permanent smiley face.

Bub, who suffered complications from the bone disease, died in her sleep on Dec. 1, Bridavsky said. She was eight years old. Bridavsky, who said he’s devastated by the death of his cat, didn’t announce her passing until Dec. 3, presumably to grieve in private before getting bombarded with messages and media enquiries.

“I have always been fully transparent about BUB’s health, and it was no secret that she was battling a persistent and aggressive bone infection,” Bridavsky wrote on Instagram. “Even knowing this, we weren’t expecting her to pass so soon or so abruptly without warning. I truly believe that she willingly made the decision to leave her failing body so that our family would not have to make that difficult decision ourselves.”

“It is impossible to put into words the profound effect that BUB has had on my life, on the lives of thousands of homeless pets, and on the lives of those of you that have cared for her as if she were your own family. She taught me everything that I know about unconditional love, she brought my wife Stacy and I together, she’s the reason we have our beautiful children Rosco and Lula, and she has been a constant source of warmth and love in our lives for the past 8 years. To say that our family is devastated would be an understatement.”