August Sader is a teacher in the School for Good in the series. Although he dies in the first book's events, he manages to somehow communicate with both Agatha and Sophie at various times after his death.

Usually dressed in a shamrock suit, Professor Sader has a mane of bright silver hair and hazel-green eyes which he cannot use, as he is physically blind. Despite this, or in a way because of it, Professor Sader is a seer, who has visions of events in the future. He has a younger sister named Evelyn, who becomes a major antagonist in the second book, A World Without Princes.

When Agatha and Sophie arrive at the School, Professor Sader takes notice of both girls. He shares some of his visions with Agatha and Sophie, aware that their presence at the School could have a massive effect on both the world of fairy tales but also the girls' home village of Gavaldon. His help, however, comes with a price for him; the very act of looking into the future (or the past) ages him physically, and weakens him.

He appears in only one scene in A World Without Princes, where he allows Agatha to see part of his sister's actual past while she was a teacher in the School for Evil. He warns Agatha that Evelyn will know that Agatha has seen this, and will retaliate in some way, but he believes Agatha needs the information.

He also only appears in one scene in The Last Ever After, but this is a much longer scene where he reveals to both Sophie and Agatha the history of their mothers, and their actual relationship to each other. He also admits that he does not know the end of their story, as his visions only go to the moment of his sharing the secrets of their mothers and their own births and early childhood. He admits that the fate of their world, and of the relationship between Good and Evil depends on their choice, which he cannot foretell.

In The Ever Never Handbook, it is revealed that Professor Sader sent Deans Dovey and Sophie a note before his death, instructing them to accept Nicola of Woods Beyond into the School for Good and Evil, as 'her acceptance to our school will play a crucial role in its future survival.'