Seemingly confirming the Transformers: The Last Knight rumors, it's now being said Paramount and Michael Bay have cast King Arthur and Merlin.
It's reported Liam Carrigan will play King Arthur in Transformers: The Last Knight,¬†with¬†Santiago Cabrera¬†as Merlin.
Liam Carrigan actually played King Arthur in Once Upon a Time and is also known for Spotless, 24: Live Another Day, and The Legend of Hercules.
Santiago Cabrera is known for The Musketeers, Dexter, Heroes and played Lancelot in the Merlin TV series.
Regarding the Arthurian aspect of Transformers: The Last Knight, the rumors stated some sort of artifact that Optimus Prime is seeking is tied to Merlin. It was even said the Transformers were responsible for giving Merlin magic, and also that King Arthur's word, Excalibur, may play into the film somehow.
"Transformers: The Last Knight" has a June 23, 2017 release directed by Michael Bay starring Mark Wahlberg, Josh Duhamel, Stephen Merchant, Isabela Moner, Jean Dujardin, Jerrod Carmichael, Allen Phoenix, with Peter Cullen returning as the voice of Optimus Prime. ¬†