Changelings

Changelings are a race of creatures in Equestria that first appear in A Canterlot Wedding - Part 2 as the secondary antagonists and the minions of Queen Chrysalis. They also appear in several other episodes and IDW comics.

In When the Cold Breeze Blows Away, it would be happened when they join either Thorax or Queen Chrysalis.

Also,they would be first appeared in during the USRAC War since they would have their choice to be good or evil.