Twilight+alicorn.
In a recent(?) episode, the protagonist, Twilight, leveled up and became an alicorn princess. The bronies got pissed off at this because a) WHY IS IT DIFFERENT, b) princesses = girly = horrible terrible no good very bad, c) Tall Poppy Syndrome — Twilight was relatable when she was a lowly nerd, but now that she's all promoted and glamorous and power-holding, it's like she's one of those mean girls from high school, and d) her new design is allegedly less "cute" than her old one (even though the only difference is she got wings).
Original Twilight/
Digivolved Twilight