Three mysterious deepfake videos of Tom Cruise that have gone viral on TikTok are the high-tech handiwork of Chris Ume, a video visual effects specialist from Belgium.

The videos, which were posted last week, without an explanation or credits, from a TikTok account simply called @deeptomcruise, have drawn attention from experts and nonexperts alike for being among the most convincing examples of the genre of fake videos yet produced.

Ume took credit for having created the deepfake portions of the videos in a post on his LinkedIn page and in a message exchange with Fortune. But he declined to answer further questions about the videos, saying he and the others who had worked on them were not yet ready to talk to the press. “We’re looking for the correct way to communicate about this,” Ume told Fortune.

Because of the highly polished special effects involved, and because of the virtuoso impression of Cruise, the videos gained huge traction online, garnering more than 11 million views so far on TikTok.

Figuring out who was behind the videos became somewhat of a parlor game because no name was attached to the TikTok account that published the videos. Few people noticed that Ume had quietly posted links to the videos on his LinkedIn profile with the winking comment “never thought I’d be sharing a tiktok channel on my linkedin ;).”

Ume is, however, credited by name for applying “deepfake effects” to a video published in mid-January, before the latest batch, that also depicted Tom Cruise. In it, Ume morphed the face of Cruise impersonator Miles Fisher into a deepfake of Cruise’s face at the end of the video.

The YouTube video, written, directed, and edited by Stephen Vitale, according to the credits posted alongside it on YouTube, shows Fisher as Cruise conceding a fictional election bid for the U.S. presidency. A separate accompanying video Ume created shows some of the technical process he used to create the deepfake.

Although Fisher has not publicly acknowledged playing Cruise in the three viral TikTok videos, the actor has been flagged by another Cruise impersonator and social media sleuths as the person whose hands, body, and voice are used to depict the celebrity.

Ume had also taken an August 2019 video of Fisher’s, in which the actor portrays Cruise announcing his presidential bid, and updated it using a deepfake so that Fisher’s face becomes Cruise’s. He later published a video on his YouTube channel showing this deepfake video in split screen with Fisher’s original to showcase how seamless the deepfake was.

Ume is well-known among the small circle of visual effects artists and machine-learning experts adept at creating extremely high-quality deepfake videos. He is part of the Deep Voodoo Studio, a kind of dream team of deepfake wizards assembled by South Park creators Trey Parker and Matt Stone, and English comedian, actor, and director Peter Serafinowicz for their show Sassy Justice, which debuted on YouTube in October 2020 and featured deepfakes of dozens of celebrities and politicians.

According to Ume’s professional website, he prides himself on the quality of his work. “I create the craziest videos and love humor,” Ume says on the website’s “About” section. “My talent is my eye for perfection and my high quality standards. I’d rather finish something I’m proud of than quick garbage.”

In an interview about deepfakes for Philadelphia PBS television station WHYY that is posted to Ume’s website, the visual effects artist argues that deepfakes are an exciting new tool for creativity. While some technologists and security experts fear deepfakes will become a potent weapon for political disinformation, Ume downplays such concerns. Consumers just need to become more skeptical of what they see, he argues.

“People just have to learn to be more critical—that’s the point,” Ume told the interviewer. “They don’t have to be scared of deepfakes, because it probably existed even before you heard the word ‘deepfake.’ You just didn’t know it. At least now, you know it exists, and you know you shouldn’t believe what you see.”

Ume’s website and social media channels showcase more than a dozen deepfakes he’s created, depicting everyone from rapper Snoop Dogg to Queen Elizabeth II.  

Deepfakes are highly realistic fake videos created using a kind of artificial intelligence. They often involve swapping one person’s face for another’s. The technique used to create them is called a GAN, or generative adversarial network. This involves taking two neural networks—a kind of A.I. loosely based on the human brain—and training them in tandem. One network learns from a database of images or videos, usually of a famous person, how to generate new facial imagery of that person. Meanwhile, the other network is trained how to pick out the target person from a database of many different people. The first network tries to generate new images that are good enough to fool the second network into correctly classifying them as real images of the deepfake target.

Ume, who trained in visual effects at university in Belgium, came to the attention of the Sassy Justice team thanks to a viral video he created in 2019 in which he used a deepfake of actor Kit Harington, who plays Jon Snow in the hit television series Game of Thrones, and had the fake Snow apologize for the series’ final season, according to a promotional post for an upcoming lecture Ume is giving to students at the Artevelde University of Applied Sciences in Ghent, Belgium.

The deepfake effects master also received some press attention for a 2019 video in which famed Belgian singer-songwriter Jacques Brel, who died in 1978, is seemingly resurrected to sing a new version of one of his songs—actually a cover version sung by current Belgian artist Alain Smits.

The current trio of fake Tom Cruise videos has been praised as some of the most believable deepfakes ever created. “These are incredibly well done,” Hany Farid, a professor at the University of California at Berkeley who specializes in digital video forensics, told Fortune.