Screen legend Sir Anthony Hopkins has written a gushing fan email to Breaking Bad actor Bryan Cranston after binge-watching every episode of the Emmy Award-winning show in just two weeks.

The Academy Award-winning actor described the performance of Cranston, who plays a high school science teacher turned methamphetamine manufacturer, as the "best acting I have ever seen - ever", praising the "epic" show for restoring his confidence in the industry.

The 75-year-old said it was nearly midnight in Malibu when he finished his marathon viewing session, and he felt compelled to sit down immediately and write the email, which begins: "Dear Mister Cranston".

The letter, which Hopkins' agent has confirmed is legitimate, is filled with praise and sincere admiration for Cranston and the entire cast.