1 of 10
2 of 10
JACK THE CAT
When New Yorker Karen Pascoe needed to relocate to California, she checked her two cats with American Airlines at JFK Airport. One of them, Jack, went missing, which mobilized concerned pet lovers to set up a Facebook page to help find him. Eight weeks later, Jack was discovered, but was severely malnourished. The 7-year-old male eventually succumbed to his life-threatening infections and died.
3 of 10
This young Emporer penguin's saga began in June, when he was found disoriented on a beach in New Zealand, nearly 2,000 miles from his home in Antarctica. After recuperating for two months at the Wellington Zoo, Happy Feet was released into the Southern Ocean. What has happened since is unknown; the bird's satellite tracker stopped transmitting in September.
4 of 10
BRONX ZOO COBRA
She wasn't just venomous, she also went viral. A female cobra snake at the Bronx Zoo went missing for seven days, and though she was later found "coiled sort of secluded in a dark corner" without having hurt anyone, she managed to blow up – on Twitter, and everywhere else on the web.
5 of 10
NAVY SEAL'S LOYAL DOG
The loss of 20 Navy SEALs in a helicopter crash in Afghanistan became immediate and personal when a photo surfaced of Petty Officer John Tumilson's dog laying by his owner's coffin. The Labrador retriever, named Hawkeye, was later adopted by Tumilson's good friend.
6 of 10
CHIMPS SEE DAYLIGHT
When an Austrian pharmaceutical company changed ownership this year, a group of chimpanzees that had been used for medical research for 30 years was released. They had never before seen the outdoors, and for the first time, they felt sun on their faces, put their toes in the grass and grinned from ear to ear.
7 of 10
TROUBLE HELMSLEY DIES
After bearing the burden of 12 million heavy dollars on her tiny shoulders for four years, Leona Helmsley's dog, Trouble, died in June at age 12.
8 of 10
COLORADO CAT WILLOW
How does a cat get from Colorado to New York and end up back in her original owners' arms five years later? The answer's still not clear. But once Willow was reunited with her family, she became a celebrated kitty, going on to appear on the Today show and meet Anderson Cooper.
9 of 10
HEIDI THE CROSS-EYED POSSUM
She was supposed to have been the next Knut, but Heidi's fame was short-lived. Her unique condition earned her a place in the spotlight in Dec. 2010, and by the end of September, she was dead.
10 of 10
Though turtles at New York's JFK Airport cause delays every year due to their annual breeding patterns, 2011 turned out to be the year for the turtles, who got on Twitter and took off.