Actors often, if not always, portray characters that aren’t the age they really are in real life. This can be masked through makeup and special effects, at least when the difference is significant, but usually the difference is not of visual significance. Someone can be 35 and play a character that’s 25 or 40.
Some differences, though, are far more significant, making us think the actor must really be of that age. To our surprise, this isn’t the case, and many performers end up acting well above their age. They can be child actors or seasoned veterans, what matters is that they’ve convinced us of being much older than what they were.

Laurence Fishburne in Apocalypse Now
Fishburne was only 14 when filming began, despite convincingly playing an older soldier during the Vietnam War. Many viewers assume he was already an adult because of the movie’s intense subject matter and his mature screen presence.

Orson Welles in Citizen Kane
Welles directed, co-wrote, and starred in Citizen Kane at just 25 years old, astonishing audiences who often assume someone much older created such an ambitious and technically influential masterpiece.