As expected, the internet sensation - known for her down-in-the-mouth expression and slightly bulging eyes - remained looking unhappy on her birthday on Friday while touring New York City with an entourage worthy of Hollywood.
And Hollywood is where the sour-looking feline is bound, with a film deal in the works to add to her many endorsements and licensing deals that include her scowling face on limited-edition bags of Friskies Party Mix treats and her own "Grumppuccino" bottled coffee drinks.
So who will voice the cat we love to caption? Grumpy's not saying, nor are her humans - the brother-sister team of Tabatha and Bryan Bundesen.
With her own agent, YouTube videos that have attracted millions of hits, T-shirts, calendars and a best-selling book available in 14 languages, exactly how much is this cat worth?
"The business is doing very well," Bryan laughs. "Grumpy doesn't like to discuss specifics." The humans, to be sure, are more than a little grateful.
"We both were blue-collar people," Bryan says - he was laying cables for a cable company in Ohio and she was a waitress at a Red Lobster restaurant near her Morristown home, in Arizona.
"It has changed our lives: it's been a blessing. We're very thankful for it."
Grumpy's real name is Tardar Sauce - dubbed (and misspelled) by Tabatha's now 12-year-old daughter, Chyrstal, soon after their female pet calico gave birth to her and three siblings.
The cat was tiny, and is still petite - a victim of feline dwarfism - and wobbles a little when she walks because of her elongated rear legs, which have only added to her popularity.
"She looks like a Snowshoe Siamese is what we're told most," Bryan says. "We've had comments from people about it being nice the spotlight's on a cat that's unique and has feline dwarfism.
"A lot of people are happy that it kind of spreads the message that it's OK to be different. She's also such a happy cat."
Had Bryan not put Tardar's photos on social networking website Reddit in late 2012, then later followed up with videos when their authenticity was questioned, she might never have become a phenomenon.
"People said her face was Photoshopped," he says. They posted videos on YouTube to prove otherwise and earned about 1.5 million views overnight. Now, Grumpy's YouTube channel has had more than 25 million views and 200,000 subscribers.
"There are a lot of cats on the internet, but there's no competition," Bryan says. "She has the grumpy market cornered."