Tumblr and The Sims Resource are my main sources for fantasy CC. DanSimsFantasy has a lot of wonderful fantasy accessories and outfits for fairies and mermaids. Link to his page: https://www.thesimsresource.com/members/DanSimsFantasy/
There's another CC artist who does very amazing fantasy makeup. She even does fantasy eyebrows. Link to her page:https://www.thesimsresource.com/members/tatygagg/
Others creators whose fantasy CC I've really enjoyed that I'm including as you've just kind of generalized "fantasy CC": Tekri Sims, StardustSims, Pyxis, plazasims. Tekri Sims has a lot of multi-colored cute hairstyles, Disney princess hairs down to the exact detail, even rainbow and pastel rainbow hair colors that are very adorable. StardustSims does a lot of Disney content as well. Pyxis does some skin details and other facial features for fantasy character builds, especially animal hybrid type builds. plazasims does a little bit of everything. She has some really great Halloween items, great fantasy effects for build-buy mode and even some video game/comic book cosplay. I hope this helps. Bellassims also has a mermaid themed pack of CC for furniture if you're interested.
