Following Johnny Depp's exit from the Fantastic Beasts franchise, there can be no better choice to play the villainous Gellert Grindelwald in Fantastic Beasts 3 than Colin Farrell. The Irish actor played MACUSA Auror Percival Graves in the first film, Fantastic Beasts and Where to Find Them. However, the ending revealed that he was actually Grindelwald, having changed his appearance through the use of transfiguration to assume Graves' identity.
After losing a libel suit against British tabloid The Sun over allegations of domestic violence against his ex-wife, Amber Heard, Depp said that he had been asked to resign from the Fantastic Beasts franchise by Warner Bros. Though he maintains that the allegations are false, Depp said that he "respected and agreed to that request." The departure of one of Fantastic Beasts' stars is the latest bump in the road for the prequel series, which has struggled to draw the same interest and success as the original Harry Potter film series. Fantastic Beasts: The Crimes of Grindelwald became the lowest-grossing Wizarding World film upon its release in 2018, production on Fantastic Beasts 3 was halted at the last minute due to the COVID-19 pandemic, and Harry Potter author J.K. Rowling has been embroiled in controversy over transphobic remarks.
When Farrell's Percival Graves transformed into Depp's Grindelwald at the end of Fantastic Beasts and Where to Find Them, the response from audiences was largely one of disappointment rather than excitement. Even outside of his legal problems, Depp has seen a decline in popularity in recent years, appearing in a string of box office bombs and critical disappointments like Alice Through the Looking Glass, Transcendence, and Mortdecai, and his penchant for roles with colored contact lenses, a painted white face and strange hair has grown rather predictable. Farrell's subtle but electric performance as Percival Graves was one of the highlights of Fantastic Beasts and Where to Find Them, and Depp's arrival brought with it the disappointment of Farrell's departure.
Farrell has incredible range as an actor, mastering everything from dark comedies like In Bruges and The Lobster to intense thrillers like Phone Booth and Widows. However, he truly shines in villain roles. Graves' tender and unsettling grooming of Ezra Miller's lonely, downtrodden Credence Barebone in Fantastic Beasts and Where to Find Them demonstrated Farrell's talent for playing seductive villains, as also seen in the 2011 remake of vampire movie Fright Night. His final speech, in which he challenges laws against revealing the wizarding world to muggles that force wizards to "cower in fear unless we risk discovery," is delivered in such calm and compelling tones that even the audience may find themselves becoming convinced.
There was always a possibility for Farrell to return as the real Percival Graves, since the Fantastic Beasts movies never confirmed that Grindelwald killed him before assuming his identity. But while Farrell would be welcome in any role, bringing him back as Graves would lose the chilling edge that he has when playing the villain. With Fantastic Beasts 3 now in need of a new Grindelwald, the story could easily justify him assuming Graves' appearance again - whether to taunt MACUSA by wearing the face of their former colleague, or to deepen Credence's loyalty to him by reminding him of when they first met.
Grindelwald is a powerful figure in Harry Potter canon - Dumbledore's childhood friend and the love of his life, and also basically the Adolf Hitler of the wizarding world. What's particularly frightening about him in concept is not simply his powerful magical abilities, but his ability to draw in devoted followers to his cause. Warner Bros. is reportedly planning to recast the role following Depp's departure, but the Fantastic Beasts movies already have a perfectly beguiling version of Grindelwald who could be brought back instead.