These toys combine superheroes and villains with trains for an oddly satisfying mash-up

Mash-up toys are starting to become quite popular. Last year, Hasbro unveiled a Chewbacca Furby, cleverly named Furbacca, and recently Hot Wheels has been rolling out "Star Wars" mash-up vehicles.

Last year, at San Diego Comic-Con, I came across a strange combination when I was handed a button featuring a Thomas the Tank Engine character designed as Batman.

What did it mean?

Fisher-Price started rolling out a few of the trains last year with basic fan favorites like Batman, Superman, and the Joker under a line called Thomas & Friends MINIS.

"You don't have to dig too deep to find that kids (and adult fans) create their own narratives on YouTube and through social media on a daily basis; and this often involves mixing up Thomas' world with others as well. So it's already being done, and consumers have already given us permission to do so," Michael Pisors, director of global brand marketing for the Thomas & Friends toy team at Fisher-Price, explained in an email to Tech Insider.

The toys were a hit. Walmart sold over 5 million of the mini-collectibles alone. So this year, Fisher-Price is rolling out over 35 new DC Super Friends mash-ups which will begin to be released in February. They'll be in Walmart for the first half of the year before expanding to other retailers.

Check some of the mash-ups out below: