This is the Minifigure version of Ariel, from the firs Disney Series of blind bags. There are also some versions of Ariel that are Minidolls (and I actually prefer these), but this was the first one to come out.
Ariel from the LEGO Disney Series 1 appears in these sets:
71012 The LEGO Disney Series 1 CMF (Complete Series of 18 Complete Minifigure Sets) (2016)
Ariel is the prettiest, and youngest daughter of the king of Atlantia, an undersea kingdom. She longs for the human world, and when she turns 16 she falls in love with Eric, a true human. To pursue her passion, she meets Ursula, who grants her wish, but at a serious price.
- Ariel’s best friend is Flounder the guppy fish.