Not only do half of them date each other, but they're all best friends too.
So when Charles Melton - who plays Reggie Mantle - celebrated his 28th birthday on January 4, they all made it their mission to give him MAJOR love on social media.
"it’s my birthday," he wrote on his own timeline.
But, it was his girlfriend Camila Mendes who posted a tribute to him first. Sharing a super sweet photo of the pair posing with Samurai outfits.
"happy birthday @melton i will always protect you 💖" she wrote.
Lili Reinhart posted a photo of Charles from set.
KJ Apa posted some sweet photos of him and Charles hanging out.
Cole Sprouse posted a really funny pic of Charles bent over a cab.
"Happy birthday to my favourite jawline @melton. Proud of the huge steps you've taken this year. Here's him breaking his leg in real time."
Madelaine Petsch posted a hilarious selfie Charles took.