In the era of blockbuster filmmaking, CGI is almost impossible to live without - but here are 20 examples of movies using visual effects that you may not have known about. When most people think of the role CGI plays in movies, they'll look to major examples of it being used to bring to life otherwise impossible creations. Filmmakers are able to create characters as big and defined as Thanos in Avengers: Infinity War, worlds as imaginative as Avatar, or even photorealistic animals as in The Jungle Book or War for the Planet of the Apes.

This area of post-production has only become more complex, too, as the use of motion and performance-capture technology rises. As striking as the best CGI is, though, there's almost nothing that can hurt a film as easily as poor VFX. Just look at the fiasco surrounding Henry Cavill's upper lip in Justice League. Thanks to time constraints, limited budgets, or compromised visions, there are plenty of examples of CGI elements in movies not working. However, on the complete opposite side of this spectrum is CGI so good that you don't even realize it's happening.

Related: How The Lion King's CGI Changed In New TV Spot

The latest Screen Rant video featured at the top of this post takes a look at 20 moments exactly like this, where the CGI is almost completely unnoticeable. The examples are vast, with different films showing the ability to expertly create new landscapes and locations, change the appearance or performance of actors, or even take advantage of CGI as a shortcut to pulling off otherwise challenging scenes.

Clare-Hope Ashitey in Children of Men

Of all the examples that were mentioned in this video, David Fincher's ability to perfectly duplicate Armie Hammer for The Social Network is probably the most well-known example of how CGI can be used to do something that is otherwise impossible. Instead of finding two equally talented twin actors, Fincher was able to use CGI to add a second version of Hammer into the film so that the Winklevoss twins could be brought to life. As the video also showed, Alfonso Cuarón created a completely digital baby for Children of Men and Sam Raimi's Spider-Man 2 used CGI to get Doc Ock's death scene.

As this video demonstrates though, the capabilities of CGI are limitless when done correctly, but they can also raise some questions about what should be allowed to be changed. For instance, Jennifer Connelly's performance was changed in Blood Diamond to add tears during the emotional goodbye, so should there be a limit to what aspects of a performance can be changed in post-production? The decisions to reduce Lindsey Lohan's chest size in Herbie: Fully Loaded and making Natalie Portman's fingers longer in Black Swan also raise their own sets of questions.

These changes were well-done regardless, but Hollywood pulls off lesser known feats all the time. Digitally replacing the face of a stunt double with that of an actor, using green screen to create exteriors of buildings, and removing mics, harnesses, or wires that are attached to actors all happen frequently. Of course, this list only scratches the surface of seamless CGI and will continue to gain worthy additions to it as technology improves.

More: Marvel Video Highlights the MCU's Overuse of CGI