In Epic given Queen Tara's held her position for a century, both she and Ronin (on account of being childhood friends) look very good for beings which have not only lived a century but, due to their heightened speed, must actually experience that period of time as being at least twice as long as it is for humans.
A cut scene from Madagascar revealed that Ridiculously Cute Critter Mort, who behaves and, at least to human eyes, looks like a toddler, is actually 35. Justified in the looks arena because he's a mouse lemur, which are all small, fuzzy, and big-eyed. No excuse for his childlike behaviour beyond Rule of Funny.
The twins in 9 look and behave like the youngest members of the group, but with the Numerical Theme Naming their names (3 and 4) would imply that they're younger only than 1 or 2, each of which have their apparent ages made a point.
Sid from Toy Story is probably in his late teens based on what he seems to be allowed to do (buy an explosive rocket, use explosives, etc.), and because of his expert 'skills' with altering toys. Either that, or he has bad parents. However, he doesn't look any older than 15.
Baby Herman from Who Framed Roger Rabbit looks like a toddler, but off-camera acts more like a gruff, cynical, womanizing middle-aged man. As he puts it to Eddy, "I got a 50-year old lust and a 3-year old dinky."
Charles Muntz of Up is likely over 100 years old, but still looks at least like a man in his seventies.
Lord Shen in Kung Fu Panda 2 appears to be in his early twenties, but the fact that he was exiled for twenty years and looked the same then would instead put him in his forties.
The pairing of Steve Carell and his twenty years younger costar Anne Hathaway in the movie Get Smart might have made the romantic subplot a bit icky, if not for Hathaway's character explaining that the Magic Plastic Surgery that completely altered looks also took years off her apparent age and that she was in fact not much younger than him. As a plot point, it also serves to explain their pairing (99's plastic surgery and Smart's lack of experience made them the only two agents KAOS didn't know after Control was compromised.)
In Inception, Both Cobb and Mal were in Limbo for around 50 years, making them mentally in their late 70s to early 80s. Saito too. And, depending on how long Cobb was in Limbo hunting him, he may be north of a hundred by now.
Austin Powers was frozen in the 1960s, and had to have been in his late 20's. He was frozen for 30 years, and would be in his early 60s by 2002. His dad Nigel appeared about the age Austin would had he not been frozen.
The Curious Case of Benjamin Button. As a man who ages in reverse, in the latter half of his life, he always looks younger than he actually is. As an old man, he suffers from dementia and Alzheimer's, but he has the body of a child and eventually degenerates into infancy, at which point he dies, his version of death at old age.
In the controversial horror film Orphan, the titular character is a psychotic 33-year old serial killer suffering from a hormonal disorder which keeps her stuck in the body of a young girl. Her M.O. is posing as a young orphan girl, who ends up killing the families who adopt her (to be fair, she doesn't really plan to kill them, she's just got an extremely volatile temper, and becomes homicidal whenever she gets stressed at someone).
In Star Wars Episode I, Qui-Gon Jinn was sixty years old when he encountered Anakin.
Near Dark: "You have any idea what it's like to be a big man on the inside and have a small body on the outside?"
In Swedish vampire movie Let the Right One In, the vampire appears to be a young girl. Asked by the protagonist how old she is, she says "I'm twelve.... but I've been twelve for a long time." The movie never does reveal exactly how long...
In Airheads, 36-year old Steve Buscemi plays a twenty-something heavy metal guitarist, and ends up looking more authentic than twenty-somethings Brendan Fraser and Adam Sandler. Let's just say metal fans aren't really known for taking care of themselves.
While Christopher Mintz, as well as his character in Superbad looks appropriately like a high school student, this trope happens as a in-movie example as the liquor shop clerk implicitly assumes that her 25-year old customer is simply older than he looks.
In X-Men: First Class, Sebastian Shaw looks to be in his late forties or early fifties when Erik first meets him in 1944. He looks more or less the same when they meet again in 1962, a fact that he credits to his Energy Absorption powers. Raven also looks to be around 20 years old (even in her blue form) even though her age should be closer to 30. Hank mentions that her mutation causes her to age in a slower rate.
Wolverine. All because of his Super Healing Factor. He was born in 1823, but as of today, he still physically appears to be a buff as hell mid-to-late 30s. His powers constantly rejuvenate his cellular integrity rendering him seemingly ageless. He's not by any means immortal, he just ages at an incredibly slow rate, if at all.
Since X-Men: First Class is in the same continuity as the original films, Mystique would also qualify an another extreme example, being played by Rebecca Romijn despite being only a few years younger than Magento and Xavier. Justified by her ability to shapeshift (why age if you never have to?) and a comment made in First Class about her mutation slowing her aging.
Done retroactively with Moira McTaggart. In X-Men: First Class she is shown as almost the same age as Charles Xavier, but in the original X-Men trilogy Charles was played by Patrick Stewart whereas the lovely Olivia Williams played the modern-day Moira in X-Men: The Last Stand. Stewart is 30 years older than Williams.
Given the reveal in X-Men: Days of Future Past, that Toad was a soldier in Vietnam, he was somewhere in his forties during X-Men. Ray Park was only 26 at the time.
Eowyn was startled to realize that Aragorn was over eighty years old.
Kruger from Elysium. According to supplementary material, he was born in 1970, making him almost 200.
This is also implied with Delacourt and the other members of Elysium's elite. It's one of the theories regarding why Immortality Immorality pops up: you let one generation live too long in power, they're going to get really corrupt and ego-maniacal.
In Another Time, Another Place this may overlap with Dawson Casting, since Janie's age is never actually clarified. She looks about 19 or 20 at a push, and even younger in certain lights. Phyllis Logan was actually 27 at the time the film was made, so she could be anywhere between 18 and 30.
Steve Rogers (a.k.a. Captain America) falls into this. It's implied that the reason he survived crashing the Valkyrie and becoming a Human Popsicle is because of the Super Serum he was given - not only is his body in perfect condition, but his aging process was paused during his time in the ice, so in the present day, he is still physically in his mid to late 20's despite being born in 1918.