A dead alien in the refrigerator. Zombies on the loose. A mythical beast in the hills.

Scenes straight out of pulp magazines lurk in the back alleys of Chinese social media, where they can quickly find an eager following and, almost as quickly, earn a rebuke from skittish authorities.

Science fiction and fantasy tales have been growing in popularity in China, where some creative efforts have earned official endorsement. Vice President Li Yuanchao met this week with authors — including Liu Cixin, who wrote the Hugo Award-winning novel “The Three-Body Problem” — and called on them to inspire young people’s interest in science and encourage “faith in realizing the Chinese Dream,” the state news agency Xinhua reported.

But even as the Chinese leadership offered praise for the writers, the police have been less tolerant of social media users’ flexing their creativity. Several people have been punished in the past few years for relaying tales of the walking undead and extraterrestrial invaders for fear of touching off public panic.

Here are some of the online rumors that have been met with penalties in China.

There’s a Zombie in Guangzhou

Earlier this month, the police in the southern city of Guangzhou published a notice online that images posted on Weibo of a woman covered in blood and a note suggesting she was a zombie were fake. The online warning added a reminder for residents to avoid hallucinogens.

A 21-year-old man from the area with the surname Zhang was given 10 days of detention for posting the item, the Guangzhou Daily reported. The images were actually from a film that was shot in Jiangsu Province, the newspaper said.

There’s Also a Zombie in That Sarcophagus in Henan

In 2014, photos of a mummified corpse circulated online with suggestions that they were evidence of a zombie found in the eastern city of Nanjing or in Jianli County in Hubei Province. The police said the images were of an archaeological dig the year before in Henan Province that turned up the well-preserved body of a Qing dynasty official, but no signs of the undead.

A Mythical Beast Is Roaming Beijing

Also in 2014, photos emerged showing a Gollum-like creature kneeling in a rocky ravine with a message declaring that it was a “mythical beast” discovered in the Huairou District of Beijing. The local police said the images were merely candid pictures of an actor in a film who was photographed going to the bathroom while in costume, the website of People’s Daily reported.

There’s an Alien in the Fridge

In 2013, a farmer in Shandong Province claimed to have encountered five extraterrestrial creatures, one of whom was killed by an electric fence. The farmer’s story, and photos of the purported alien corpse he kept in a freezer, drew widespread attention online. The local authorities investigated and held a news conference to announce that the dead alien was actually made of rubber, Southern Metropolis Daily reported. The farmer was sentenced to five days of detention for disturbing public order, Xinhua reported.