Marge
This security guard was an adult female Human who worked at the concert hall as one of the two known security guards, the other being a rather gruff individual.
History
She was present in Sunset Shimmer's selfie-drone video and rolled her eyes at the (middle aged) teenagers use of slang.[1]
During a music festival, she served as the only known security guard who made sure the eager fans weren't bringing along any weapons or other dangerous goods. There, she was deeply confused as to how Pinkie Pie had such huge balloons in her bag.[2]