It's hard to tell who started the trend, but the premise is fairly simple: Users who look uncannily like celebrities or television characters are sharing videos of themselves "in character."
One viral example is Eric Schultz and TikTok user livvy.lady, who Buzzfeed identified as college student Liv Artensen, who bear a strong resemblance to the famous "Office" couple Jim and Pam, originally played by John Krasinski and Jenna Fischer. Eventually, the duo paired up to reenact some of the couple's most famous scenes.
“Okay, so if and when there’s a reboot...they’re casting y’all...right???” one fan wrote in the comments. “Y’all are their doppelgängers.”
Another TikTok user, who goes by Ashley on the app, looks similar to Taylor Swift. She posted videos of herself lip-syncing along to Swift's hit songs.
Other look-alikes aren't acting out specific scenes or doing impersonations; They just happen to look like celebrities or characters.
Take user Danielle Collins, who shared a video of herself morphing into the Olsen twins. In a selfie, she looks exactly like the sisters.
"I get this all the time and I don't really see it," she wrote.
Commentators quickly jumped on the similarities between Collins and the twins.
"That is the same person omg," wrote one user.
"Girl why didn't you just try out for Fuller House," added another.
Another TikTok user, Sonja Lovdal, who looks just like Maisie Williams as Arya Stark, has plenty of fun making videos that react to the comparison.
In another video, Lovdal joked that she was the knockoff version of the beloved character.
It's not just modern celebrities either. TikTok user Chloe McGowan shared a video comparing herself to a young Lindsay Lohan, and the two couldn't look more similar.
Commenters joked that McGowan might be a "third triplet," referencing "The Parent Trap" where Lohan played both twins.
It's hard to tell whether the trend is just some fleeting fun for users or something more permanent - but with millions of #LookAlike posts and billions of views on the topic, it seems like TikTok users are happy however long it lasts.