This Hermione Granger's men fan art contains
cocktail dress and sheath.
There might also be
dinner dress, dinner gown, formal, evening gown, strapless, bare shoulders, and gown.
Basically a video where the son of Voldemort, Caleb Riddle, goes to Hogwarts and tries to lead a normal life, despite his heritage. He falls for Hermione (awwww) and Voldemort tries to get him to join the Dark Side. It's a bit long, but worth it.