My favorite is Stacey Dash, who quite believably played a teenager in 1995’s movie Clueless and followup TV series from 1996-99, despite being born in 1966.
Gabrielle Carteris was one of the teens on Beverly Hills 90210 and she was 30.
Guess I should start paying attention to her eyes. 
I’m pretty good at judging the age of people who were born within 4 or 5 years of when I was born. So, when someone my age is cast as being even slightly older or younger than they really are, it snaps my sense of belief. (The same is true when I see someone who is clearly not my age is cast in a part that is supposed to be my contemporary).
But people who are more than 5 years older or younger - I really can’t tell exactly how old or young they might be. Just “younger than me” or “older than me.”
I have a feeling that a number of casting directors are the same. At the casting directors’ ages, 17, 22, 25, it’s all the same to them, all of those people are young kids in their eyes.
How do you know that teenage wizards don’t all look older than they are?
You know, to avoid being carded and all.
Malcolm McDowell played a 15yo at 28 or so.
A casual review of the IMDB entries for Beverlie Hills: 90210, High School Musical 2, American Pie and The OC revieled that actors in their early 20s or older playing high school students is the norm, not the exception.
Aside from the acting experience issue, I have another theory:
Attractive women age 16 to 30 tend to all aspire to look like they are around 22. Therefore, baring physical indicators like laugh lines or crows feet (which are mostly covered up with stage makeup anyway) it is very difficult to tell the actual age of a young looking, skinny, petite woman on screen.
Actual teenage guys on the other hand, look like skinny dorks, no matter how cool they are in their high school world (unless they look like they are 26 anyway). If you ever watch MTV’s Made or any other high school documentary show, the kids LOOK like children.
So IOW, early 20s are the perfect age to play high school kids because to actual high school kids they look cooler and to adults they still look believeably younger.
In the movie Superbad the three leads were 19 (Michael Cera), 18 (“McLovin”) and 24 (Seth). They were playing high school seniors so the Cera and McLovin weren’t too far off but Seth didn’t seem like he was 6 years older than McLovin at all.
In “Freaks & Geeks” the kids ages were all over the map. The guy who looked the oldest (Franco) for his age was 21 and the girl who looked the youngest (Lindsay) was 24.
Dana Hill, from the “National Lampoon’s European Vacation” and “Shoot The Moon” played young teenager roles quite convincingly.
Yeah, but no one I know bought her as a high school student. Does she look 18 to you?
In this photo all of them are ‘glamed’ up, which her character ususally was not.
Not that I watched the show. Ever.
Not as bad as these ‘teens’.
Elisabeth Shue pulled it off. At age 24, she played a 17 year old in Adventures in Babysitting.
This is the reason, and not because teenage kids are PITA’s. (The ones I know are very professional. Big stars, maybe not.) If the kid is under 18, they are limited in the hours they can work, the production company must pay for a tutor on the set, and parents are allowed to be there at all times. Over 18, they can usually get themselves to the set, they don’t need a tutor, and they are covered by adult union rules. (The pay is the same.) My daughter’s manager told us that work for kids pretty much dried up over 15, since adults with young faces get selected for these roles. If you’re in a role already, that’s different.
There is another danger. If you remember “Clarissa Explains it All,” while Melissa Joan Hart looked reasonably young, the kid who played her younger brother looked about 30 by the final season.
I was wondering if anyone was going to mention Melissa Joan Hart.
I remember as a teenager being annoyed at all the actors who to my teenaged eye were so clearly not teenaged, playing teenagers. As I got older, it didn’t seem as obvious.
I’d be curious to know if high-school teachers spot the 20-ish actors playing younger, more often than others do.
I remember thinking at the time that the only person in 90210 that looked like a highschool student was Douglas Emerson (played Scott Scanlon. I looked all this up on IMDB. He’s was the dorky blond guy who was friends with the token dorky kid who hangs out with the cool kids. Shoots himself in the face in the first or second season.). He would’ve been 25 or 26 at the time.
I think the main turn off for hiring real kids-going-through-puberty for kids-going-through-puberty is that unexpected things happen with their physiology.
Case in point from Harry Potter: Tom Felton (Draco Malfoy). That guy grew up between Sorcerer’s Stone and Chamber of Secrets. He’d’ve only been 14 or so at the time, but he looked too old for the role already.
My two youngest sisters both looked significantly younger than their actual ages. They’re six years apart, but when R was 18 she was the same size as S and looked about the same age. S is in her mid-30s now but has a hard time getting taking seriously in her management job because she looks maybe 18.
Why I did not inherit the Howard genes I do not know.
In fairness, when the “90210” started, most of the female leads actually were teenagers, aside from Carteris, who was 30 and looked it.
That picture of all of the 90201 kids looks like a shot of a bunch of 20-somethings. I never saw the show, so if you asked me , given that cast, what kind of show they would be making, I would have said “something like Friends.” Of course, the clothing could be misleading, because it’s very early 90s, but I can’t buy it. I know way too many 20-somethings that look a lot younger than that crew.
I don’t think it’s a problem for Harry Potter. The alternative is getting a new cast of kids, and that’s way more distracting and weird. We just have to go with it and forbid Dan and Rupert from, I don’t know, growing full beards or something. 
I don’t think the Harry Potter franchise will have a problem. In the last two books the characters are 17/18 - exactly the age of Miss Marcus and her friends. Looking at them as a group there is enormous variation, some of them, some of the time could be in their 20’s, other times they still look very teenagery. Mostly depends on what they are doing.
Also, Harry and his friends haven’t had the easiest of childhoods :eek: - I think they’re entitled to look fairly mature for their age.