Technology is really amazing.
When I was a kid, we were still using puppets and men in suits to make movie monsters. Now, they're all made on the computer.
In fact, a surprising amount of what you see on a movie screen is added in after filming wraps.
And photos from the set show just how different things look in real life:
Life of Pi
Alice In Wonderland
Pirates of the Caribbean: Dead Man's Chest
Rise of the Planet of the Apes
For a closer look at how the cast transformed for the movie, check out this behind-the-scenes video.
The Wolf of Wall Street
For this shot, the lion was real but his human co-stars were added in later.
Game of Thrones
Of course, this HBO fantasy show isn't a movie, but it relies on special effects as much as any blockbuster.
Including when its actors transform into their characters.
Beauty and the Beast
If you really want to appreciate Emma Watson's performance, you can watch them tape this scene before the beast's costume is added on.
Oz the Great and Powerful
The Harry Potter series
Quidditch is obviously tricky to film...
And so are floating books.
The Jungle Book
The Great Gatsby
The movie's gravity-defying scenes were pulled off using giant, rotating sets.
You can see the set in motion in this video.
Man of Steel
Guardians of the Galaxy
The Twilight Saga: Eclipse
The Lord of the Rings
300: Rise of an Empire
Teenage Mutant Ninja Turtles
Iron Man 2
Notice: Chris Evans is shrunk down to play his scrawny character before he transforms into Captain America.
If these pictures surprised you, maybe you missed these 10 Tiny Details From Ferris Bueller's Day Off too.
And if you're craving more before and after photos, find out what these 21 Child Stars From the '80s Look Like Today.