Liam Neeson's brilliant portrayal of Ra's al Ghul in Batman Begins (2005) depicted one of Batman's greatest mentors, and one of his toughest enemies. If Ra's al Ghul were to be portrayed alongside Robert Pattinson as Batman, that actor will have tough shoes to fill. However, there are a couple of actors capable of taking on the role of the Caped Crusader's mentor/villain.
In Batman Begins, Ra's al Ghul is a complex character because he and his army, the League of Shadows, operate in such a secretive manner. Ra's and his league can take down enemies without them realizing what hit them. When Ra's encounters Bruce Wayne, he offers him a path to salvation, teaching him how to take down criminals without being recognized. Ra's tells Bruce that he can become "more than just a man" and have the potential to be legendary and unstoppable (leading Bruce to begin his journey towards becoming Batman).
Those lessons from Neeson's portrayal of Ra's are so striking because, even though he will, unfortunately, become Bruce's enemy, he did train Bruce in becoming a powerful man with "a particular set of skills" (another classic line from Neeson's great action film Taken). From Ra's, Bruce learns martial arts, how to use weapons like swords and gauntlets, how to hide and sneak up on opponents, and, most importantly, how to confront personal fears.
While Liam Neeson was perfect in the role, there are middle-aged actors who are qualified to take on the role opposite Robert Pattinson's younger Batman. Mads Mikkelsen is a terrific choice because, like Neeson, Mikkelsen can portray characters, especially villains, with the qualities of a gentleman. A few years ago, he brought class and strength in the role of Dr. Hannibal Lecter, who's a villain, a vigilante, a strong and skilled killer, and a gentleman who could take on anybody and read other people's psyche.
As Ra's, Mikkelsen could portray the character as a strong and disciplined mentor to Batman, teaching him how to fight with precision and power, especially after seeing Pattinson's Dark Knight mightily punch a Gotham villain several times in the face in the first trailer for The Batman. Mikkelsen is also no stranger to comic book movies, portraying a powerful villain in 2016's Doctor Strange. It's unclear how Ra's will be incorporated into this potentially new Batman franchise, but Mikkelsen can not only bring the seasoned look of a mentor, but also a villain with a diabolical plan to crush Gotham city.
However, since Neeson's Ra's already tried to destroy Gotham, perhaps Milkelsen's portrayal could go for more personal vendettas, like going after Batman and all of his close allies, including Commissioner Gordon. Mikkelsen's Ra's also has the opportunity to provide more backstory into the character, and how the League of Shadows was formed, as well as the training he provides Bruce Wayne. These could likely be presented in flashback sequences, and then Ra's can fight Batman years later in the present day, as both men seek vengeance.
Although, based on the trailer for Pattinson's Batman film, the feature appears to take place during the 1970s, with some 1940s style production design that's reminiscent of both David Fincher's psychological thriller Se7en and Joker with Joaquin Phoenix (perhaps signaling a crossover between Pattinson's Dark Knight and Phoenix's clowned prince of Gotham). By taking place in the 1970s, this potential franchise could reveal how both Batman and Ra's started out at a very young age on their similar but opposing quests in seeking justice for Gotham.
On the theme of vengeance, another actor who can portray Ra's with gravitas and power is Jon Hamm. While he may not appear to be an actor who could portray a comic book character, he was briefly considered to play the Dark Knight before Ben Affleck took on the role of Batman for Batman v Superman: Dawn of Justice. After Hamm successfully portrayed a cold-blooded, murderous criminal in the heist action thriller Baby Driver, there's no doubt that Hamm can play villains with a cold, calculating demeanor.
In Baby Driver, Hamm's role as Jason 'Buddy' van Horn initially appears as a criminal who's nice, suave, friendly, and handsome, reminiscent of a George Clooney, Steve McQueen, and Warren Beatty. He's a guy who just simply does his job robbing banks, and acts like a smooth professional. However, when his lover, also a criminal, is killed when a robbery goes wrong, Buddy reveals his angry, violent, and vengeful side as he takes on the police and Baby, the protagonist, who he blames for his lover's death.
If Hamm were to play Ra's, especially in a younger capacity, he could bring coolness and professionalism to the role, in terms of portraying a highly trained professional who can be both friendly and stern towards Pattinson's Bruce Wayne. When and if the time comes when Bruce and Ra's fight each other, Hamm could give Pattinson a good, gritty battle, especially if Bruce betrays Ra's by confronting the League of Shadows. As Ra's, Hamm can also borrow qualities from his Don Draper role in the successful AMC TV series, Mad Men (which also took place around the 1970s), in which he's a tough leader who has a lot of secrets hidden within his persona, making him a dangerous adversary for Batman.
Mads Mikkelsen and Jon Hamm are two terrific actors, and are each worthy of taking on the role of Ra's al Ghul opposite Robert Pattinson's Batman because both performers have proven that they can portray men who are physically tough and strategically intelligent leaders. They are also effective in acting as powerful men with secretive agendas, and are capable of laying out personal wrath towards Batman. For the next actor playing Ra's al Ghul, he must "become more than just a man."