David Thewlis, Gary Oldman, and Alan Rickman are all older than the characters they played in the Harry Potter films. 

Let’s look at HP: POA

During POA Sirius was supposed to be 34. Remus and Snape were both supposed to be 33. 

The Actors?  David-41, Gary-46, Alan-58 

So let’s see them if they had been the same age as their characters when they played them.

David Thewlis was actually pretty close…he was only 8 years older than Remus.

David was 33 in 1996. So….

 

Gary was 12 years older than Sirius. He was 34 in 1992.

So…

Then there’s Alan..definitely the most dramatic change. Alan was 25 years older than his character. He was 33 in 1979.

Now pics of Alan in and around 1979 were kinda hard to find. (Look at his IMDB, the first film listed from him is in 1978) But I gave it my best go and I opened my search to include 1978 and 1980.

So Alan at or around 33 is…