Hollywood Studios announced they will be hosting a special event similar to last year's Limited Time Magic event, Unleash the Villains. This new event, Villains Unleashed, is a one night only event boasting appearances of over 50 Disney Villains plus special shows, dance parties, and merchandise.
Disney reservation agents have a list of characters that are scheduled to appear. Of course, entertainment is always subject to change and three of the characters are listed as "to be determined". Below is the list that was provided. No delineation was made between meet and greet, show, dance party, or Fantasmic appearances.
UPDATE 7/23/14: The official Disney Parks Blog released another update on the Villains Unleashed Event. Two names were added. Lilo and Stitch villains Captain Gantu and Dr Hamsterviel!! Here is a link to the article Villains Unleashed Update July 23
Captain Gantu-Recently Added
Dr Hamsterviel-Recently Added
Big Bad Wolf
Maleficent (Live Action)-Recently Added
Bowler Hat Guy
Sheriff of Nottingham
Queen of Hearts
Snow Witch (Hag)