It's a little bit funny when one thinks about the fact that the "All-American" ideal character of Superman is portrayed by a British man. Henry Cavill may come from across the pond, but he's now synonymous with the role of Superman worldwide. Cavill made an impressive debut in Man of Steel and has continued to give consistently solid performances in each subsequent DCEU film that he's participated in. However, that film universe's stories have yet to really give him his due.
Henry Cavill is barely in Justice League, which is a shame, because had Superman been brought back to life sooner he may have been able to help make that film more enjoyable overall. The material that's being given to Cavill is arguably not up to the level of acting that he's brought to other films in his career. Here are a few arguments for the case that Henry Cavill's best acting surfaces in his roles outside of Superman.
The DCEU Superman Doesn't Often Show Emotion
This isn't a negative to the movies themselves, but the DCEU hasn't yet given Superman a role that requires him to display a complex range of emotions. That's not to say that he's boring or that the movies fail to capture the character of Superman correctly; they do. It's just that Superman is inherently good and a beacon of hope, even if that means that he's a bit milquetoast at times.
Cavill keeps things at an even keel with his performance, meaning that his tone rarely changes from the confident, calm, and kind character that's seen on screen. There are moments where he's able to let loose a bit more and show some rage, like in his fight against Batman in Batman Vs. Superman: Dawn of Justice. Overall though, it's pretty clear that his character is meant to serve as the anchor and moral center of the Justice League, which is why he's ultimately written to be such a wholesome character.
Cavill Can Hold His Own Alongside Major Stars
Sure, the DCEU is a big deal and playing Superman is pretty much about as iconic as it gets. But the times when Henry Cavill has been able to really shine with his acting abilities have been when he's able to stray from the path of good alongside major stars. Take his role in the most recent Mission: Impossible film for example. Not only did he grow a seriously bodacious mustache, but he also portrayed a villain.
Add in the fact that he took on and thrived in the role of a villain while also having to keep up with Tom Cruise and it's clear that his performance was no small feat. Tom Cruise has been known to dominate both the screen and the press cycles surrounding his films, mostly because he still makes it a point to do all of his own stunts. However even Cruise ended up playing second fiddle to Cavill once that mustache emerged, and his convincing turn as the villain swayed audiences.
Henry Cavill Can Handle Any Genre and Cares About Source Material
Whether he's portraying an American spy in The Man From U.N.C.L.E., a romantic lead in Whatever Works, or even the first Duke of Suffolk in The Tudors, it's clear that Henry Cavill fits in basically any genre. Most recently he's made the jump to full on fantasy with his role as Geralt of Rivia in Netflix's adaptation of The Witcher. His performance is spot-on, helping the series to succeed and secure a second season before the first even premiered.
Speaking of The Witcher, Henry Cavill even went so far as to learn how to wield a sword so that he could better embody the character in fight scenes. The way that he dances around the screen quite literally looks like the video game has been brought to life at times. He also revealed that he's a huge fan of the original book series the games are based off of and that he used this knowledge to inform his performance.
Even more recently Cavill got to take on the role of Sherlock Holmes opposite of Millie Bobbie Brown in Netflix's Enola Holmes. The tone overall is lighter here, and, oddly enough, this was one of the roles where Cavill actually had less familiarity with the source material. He's typically so engaged in doing justice to characters like Geralt and Superman because he grew up as a fan of these characters.
However, he's admitted that he didn't have as strong of an attachment to Sherlock Holmes or the books, and as a result his portrayal is refreshing. It also shows just how well Cavill fits into the tone of the movie when he doesn't have pre-existing knowledge of the source content. It shows just how great of an actor Henry Cavill is, and it's exciting to see where he'll go and who he'll play post-Superman.