The Shadowbolts are one of Nightmare Moon's shapeshifter forms in My Little Pony: Friendship Is Magic.
Friendship is Magic
They appear in the scene where Rainbow Dash was going to fix the broken wooden bridge so her friends could cross. The Shadowbolts try to tempt and deceive Rainbow Dash into join them, but Rainbow Dash, out of loyalty to her friends, declines so she fixed the broken wooden bridge so her friends could cross to the other side. Then the Shadowbolts turned into Nightmare Moon's shadowy magic form.
In the episode Rainbow Dash made a costume of the Shadowbolts with her to wear for Nightmare Night, and Rainbow Dash went off scaring all the other ponies by using a thundercloud.
- Antagonistic group of students from Crystal Prep. School in My Little Pony: Equestria Girls - Friendship Games are called Shadowbolts too, after this villainous group.