Pretty simple: Post a character name (and what they're in) and next person does the same with their character's name starting with the next letter of the alphabet.

Start: 

Annabelle in 'Annabelle: Creation'

Peppermint Pattie -- Peanuts

Olive Oyl 

You went backwards, Insomnia! :P

Quillam -- from Doctor Who

Roger Rabbit

Sabrina the teenage witch

Thumper -- Bambii

Ursula - George of the Jungle