Fans dubbed this background pony "Dr. Whooves" long ago (he normally doesn't have the scarf, but was given the name for his hourglass cutie mark and messy brown hair), and Hasbro has run with it on various bits of official merchandise. They had to drop the W to just "Dr. Hooves" in order to trademark it, but his official trading card does say that he's generally in charge of all things "timey-wimey", which I gather is a quote from the Doctor.