Original: A dark grey cell (such as the one in the "Sybill Trelawney" row in the "Deathly Hallows" column) indicates the character does appear in the novel, but has not yet been cast, or if so noted, will not appear.
Simplified: A grey cell (such as the one in the "Armando Dippet" row in the "Philosopher's Stone" column) indicates the character was not in the film adaptation.