Flash Sentry is a background pony in My Little Pony Friendship is Magic and supporting character in My Little Pony Equestria Girls. In FiM, he is part of the royal guard and seems to be the personal guard of Princess Cadence. In Equestria Girls, he is Sunset Shimmer's ex-boyrfriend and formely Twilight Sparkle's love interest.
Flash Sentry as a human in Equestria Girls
Flash next to Princess Cadance and another royal guard
Flash Sentry's band, Flash Drive, defeating the Eco-Kids in Rainbow Rocks