That's really to much of a general term because there are variants of demons such as snow women and Succubi in the anime. It'd have to be a specific species and even then S Rank are VAUNTED I mean they are badass once Joshua hits a full moon for example only really strong A Class with a lot of luck OR a S Rank with skill would be able to take him likewise he is still extremely formidable without the moon. To give you an example in the anime Dean nearly kills Moka, the main protagonist's girlfriend and High level S rank, with ease when at full power but plot said so so she was able to beat him due to Vampires being OP as long as you don't just splash water in their face.

If you want a demon may I suggest perhaps a http://rosariovampire.wikia.com/wiki/Graffiti_Demon who appears to be a B class or A Class? It doesn't have an official name so I hope that helps.