Flash Sentry is a royal guard at the Crystal empire, and also a love interest for Twilight. He only has a few lines as a pony, but his human counterpart has several more. In the human world, he's shown to play a guitar, and bump into Twilight several times. Other than this, we know very little about him or his personality.

In the human world, he wears a leather jacket with a red and white stripe across it, a white shirt underneath with his cutie mark on, denim jeans and black sneakers.

In Equestria, he is seen in his golden guard uniform, with a blue star on the front.

His cutie mark is a blue shield with a lightning bolt on it.