oldest actor to play a teenager or someone a lot younger

[pete]

emma thompson, then 35, in sense and sensibility, in which she was 19.
parry shen, then 29, in better luck tomorrow in which he was 16.

I kinda wanna shoot something involving a young-looking (maybe?) older actor, so I'm just curious as to how much disbelief people are willing to suspend and some good/ bad examples.

[UncleJoey]

Dustin Hoffman in The Graduate and Marathon Man are good (but obvious) examples.

[Myxo]

Four of the cast from 90210 were over 20 years old when it started in 1990..

Tori Spelling was 17..
Brian Austin Green was 17..
Jennie Garth was 18..
Shannen Doherty was 19..
Jason Priestley was 21..
Luke Perry was 25..
Ian Ziering was 26..
Gabrielle Carteris was 29..

[Find Your Magali]

Hmm, at the beginning of "Mr. Holland's Opus" Richard Dreyfuss is playing a guy who's only about 23-24, probably.

[GoneSavage]

Flashback sequences like that shouldn't be allowed since that's not really the point.  

I'd say all the droogies of A Clockwork Orange were too old.  It would have been so much more effective if they'd all been teenagers.

[soixante]

Stockard Channing was in her 30's when she portrayed a high school student in Grease.  Olivia Newton-John was obviously not a teenger herself in the same film.  

Robert Redford in The Natural (what an ironic title).  Soft lighting never served a more deceptive purpose than on that photoplay.

Ronald Reagan, a former U.S. President, used Grecian Formula to take the grey out of his hair.  At age 73, he was re-elected in a 49-state landslide.

[MacGuffin]

Robert Redford in The Natural (what an ironic title).  Soft lighting never served a more deceptive purpose than on that photoplay.

The character was supposed to be older than the average baseball player. He comes back from obscurity, after leaving the game for years, and is still a 'natural' ball player.

[03]

In the script, Ewen Bremner's character in Harmony Korine's julien donkey-boy is a teenager; i don`t know how legitimate an example this is, because i don`t see any evidence of this aspect of the character being left in the film.

[Weird. Oh]

Alison Lohman in Matchstick Men. Being ignorant of who she was,  I really thought she was 15 years old to be stunned to find out she was like 25 at the time she filmed the movie.

[lamas]

Robert Redford in The Natural (what an ironic title).  Soft lighting never served a more deceptive purpose than on that photoplay.

The character was supposed to be older than the average baseball player. He comes back from obscurity, after leaving the game for years, and is still a 'natural' ball player.

last time I checked, both he and Glenn Close played the same characters at the beginning of the film and they were supposed to be in their early twenties.

[MacGuffin]

last time I checked, both he and Glenn Close played the same characters at the beginning of the film and they were supposed to be in their early twenties.

Last time I checked...

Flashback sequences like that shouldn't be allowed since that's not really the point.

[lamas]

Flashback sequences like that shouldn't be allowed since that's not really the point.  

last time i checked, that stipulation still didn't make sense since it's still an actor playing a teenager or someone a lot younger.

[Born Under Punches]

From the canon of John Hughes

Judd Nelson was 29 when he played Bender in The Breakfast Club
James Spader was 26 when he played Blaine in Pretty in Pink
Alan Rudd was 30 when he played Cameron in Ferris Bueller's Day Off

[Thrindle]

Rachel McAdams in Mean Girls.  She was born in 1976...

[cron]

russell crowe in a beautiful mind, man. russell crowe in a beautiful mind.