A character from the anime/book/manga series, The Rising of the Shield Hero. She appears as a woman in her mid-twenties, with long orange hair and raccoon-like ears and tail. What makes her special in the series is that, like all "demi-humans" (referred to as half-animals in the anime), her maturity is based on how fast she "levels up" (in the world that ROTSH takes place in, it is similar to an RPG and has a similar levelling-based system.). This results in her eventually having more physical growth compared to mental growth.

In the anime, she is partnered with the Shield Hero (there are four "cardinal heroes" in the anime), Naofumi Iwatani. She and Filo (another character) often argue over him on certain matters.

Also, she gets lewded, which results in two different fanbases: the "Protect Raphtalia" fanbase and the "Lewd Raphtalia" fanbase.

when you're hungover as shit after a spending a night drunk as a skunk

Yeah don't mind the other explanation. It simply means "best girl".