Deadline's report offers no details of who Depp will be playing, but there is a suggestion that eagle-eyed viewers will be able to spot him in a small cameo in the first movie, which signals that the studio is looking to pull off a Marvel-style trick and introduce the new character in amongst the ones we know about, either in the body of the film or a post-credits tag.
With Wizarding World creator J.K. Rowling writing the script (and planning to craft the rest), and David Yates directing at least the initial two, the first Fantastic Beasts has Redmayne's Newt Scamander arriving in 1920s New York and unwittingly unleashing a host of magical creatures from within his magic case. Which isn't good news for the city's magical population, as relations are already strained between those with abilities and the Muggles of the States, known as the No-Maj.
The movie is out on 18 November and you can find out lots more about it in the current Empire.