I will never understand the fan indignation that ALWAYS follows this character. It doesn't matter where it is or what it is--if this gray pegasus is involved, someone is going to be indignant about something.
Derpy Hooves has long been understood to be a fan name or a nickname for the character. There is a lot of conflicting information about what this pony's real name is--probably because she was never meant to be named in the first place and still doesn't have an official name, from what I understand. I know the name Derpy was also adopted in studio but to avoid issues with the fact it is considered offensive to some people, it seems really unlikely Hasbro would actually have her officially named that.
Ditzy Doo WAS supposed to be the official name of the character. There are lots of sources that explain this. The nickname Derpy was given to her by fans and she was apparently called this, in the show, as a nod to her fans but apparently, officially, she is still unnamed.
Quote:
The character is called "Derpy" on-screen in The Last Roundup, detailed below. The episode's writer noted that the character's name in the script was originally Ditzy Doo, and she was requested to change the name to Derpy as a "tip of the hat" to the fans.