This is the list from
Disney Cruise Lines and they state "Although subject to change, Disney Characters during your cruise may include:".
Mickey Mouse, Minnie Mouse, Donald Duck, Daisy Duck, Chip & Dale, Goofy, Pluto, Max, Captain Hook, Peter Pan, Lilo, Stitch, Cinderella, Belle, Snow White, Princess Aurora, Princess Tiana, Ariel, Captain Jack Sparrow, Dopey
Some locales are designated as photos only. At these places, autographs will not be allowed due to time constraints. Please check with the onsite Character escort for more information.
Character Greetings are available throughout the day. Check the Personal Navigatorthe
Disney Cruise Line daily newsletter detailing all there is to see and doonce onboard the ship for a schedule of Disney Character appearances. You can also dial 7-PALS from your stateroom phone or check the message board in the Lobby Atrium for more details about Character Greetings.
http://disneycruise.disney.go.com/ships-activities/onboard-activities/entertainment/character-experiences/
Remember, you can also turn something into guest services to get autographs. Pillowcases and Picture Mats are the two main ones I hear about.