Redmayne, 33, will play Newt Scamander, who wrote "Fantastic Beasts And Where To Find Them", a textbook used by Harry Potter and his friends when they attended Hogwarts School of Witchcraft and Wizardry, reported Deadline.
JK Rowling, the author of "Harry Potter", has progressed through the first screenplay. The new film series takes place 70 years before the "Harry Potter" films.
That franchise was hugely important to Warner Bros, which is eager to get it back. Frequent "Potter" helmer David Yates will direct and David Heyman will be back to produce the film.