My initial reason for starting Sandbox.Playing Gertrude WC was that it seemed like a no-brainer to move to Trivia. After all, it's a Characters and Casting trope, sister tropes about character/actor age mismatch like Dawson Casting and Underage Casting are already in Trivia, and it intrinsically requires knowledge of how old the actors are relative to each other. Indeed, as of writing, 218/917 of all wicks (or about 1/3) and 12/50 sampled wicks (or about 1/4) are in Trivia — it's not an uncommon assumption! And unsurprisingly:

• Trivia? All examples (50/50) mention the actors' ages or age differences, which makes it BTS material.

However, the wick check presented several other problems, which I'll try to break down here. (Note: The wick check also includes examples of other men and women who are a generation removed but their actors aren't, but that's clunky phrasing, so for convenience I will use the words "mother" and "father".)

• Scope: Though the description is nobly centered on how Hollywood refuses to let women be old, the wick check showed only 13/50 or about 1/4 of examples are about a mother and child whose actors are close in age. Examples where there was no double standard (such as both parents' actors being too young, or only the actor playing the father was too young) made up 10/50 or 1/5, which isn't a significant difference.
• Actors' ages alone don't tell the whole story: Just because an actress is 15 years older than the actor playing her onscreen son doesn't mean PG is necessarily in effect, as some examples admit.
  • There may be story factors that warrant this small age gap that the example doesn't mention, such as supernatural aging, a teen pregnancy, or that the actress playing the mother puts on aging makeup and prosthetics.
  • A small age gap doesn't mean the mom's actress is too young; it could also mean the child's actor is too old. A 35-year-old actress is at a reasonable age to play a mom to a 15-year-old, but is the trope still in effect if the 15-year-old's actor is 25?
• Shouldn't this be about perception?: Tying in to the above point: the point of Playing Gertrude is not just that moms are as old as their sons, but that they look unbelievably young, and something something beauty standards. However, whether or not that applies can vary based on the actors' appearances and personal opinions (for example, a wrinkly 40 year old as the dad of a dewy 28 year old wouldn't raise questions from me). The examples don't really mention it.
• Examples that fit better on other tropes: I see some examples that fit better on Underage Casting and Hollywood Old.
• "Um, why do these mismatches matter?":
  • This trope catalogues the most miniscule age differences, for example, an actor playing the older sibling [gasp] 2-3 years younger than their onscreen younger sibling. That does not matter. There is a reason casting agents say "can play 23-28" and not "only people born in 1997".
  • Voice acting. It should go without saying but most voice actors are adults with decent vocal ranges. It should not be notable if some of them voice characters much older or much younger than them and their peers. Plus, this trope is specifically about our perceptions of how real people look, which doesn't matter in voice acting.
• Also, the laconic is just confusingly broad. "An actor/actress's character is much older than other characters in the cast, but the actor/actress him/herself isn't."

Potential Solution: There could be a valid sub/sister trope of Underage Casting where parents are obviously too young to play their onscreen kids (if not already covered by Hollywood Old). It could potentially be gender neutral (with a bias towards women) and be given a new name (the current is Trope-Namer Syndrome from Hamlet, but this trope has gotten too lost in the weeds of who is older than who to be that trope.

I am leaning towards a cut and disambiguation between Underage Casting and Hollywood Old.

Wick Check Results

• Actual description: Female character is supposed to be much older than another character (like her child), but their actors are close in age and/or her actor is younger: 13/50 or 26%
• Male character is supposed to be much older than another character (like his child), but their actors are close in age and/or his actor is younger OR both parents' actors are young: 10/50 or 20%
• Actors being younger than their characters in general, no comparison with characters from different generations: 9/50 or 18%
• Same Generation Age Mismatches: 3/50 or 6%
• Voice Acting Age Mismatches : 6/50 or 12%
• Misc. and Other: 9/50 or 18%

Others:

• Trivia: 12/50
• Mention ages: 50/50

1. Creator.Faye Dunaway: Diana Scarwid plays the grown up Christina in Mommie Dearest and is only fourteen years younger than her. Of course Faye plays Joan while Christina was a child as well. She apparently refused to wear old age make-up for scenes taking place in Joan's latter years.
2. Film.Bicentennial Man: Embeth Davidtz (born 1965) plays Little Miss (Amanda Martin), while Bradley Whitford (born 1959) plays her unmarried son, Lloyd Charney. She's not wearing any aging prosthetics until she's onscreen with her granddaughter.
3. Film.Drunken Master: Jackie Chan was 39 when he played Fei-Hong in this film. Kei-ying's actor was eight years older than Jackie and Ling's actress was nine years younger. Looking it up, Kei-ying is his father and Ling is his stepmother, though I guess she could be a younger second wife?
4. Film.Mother And Child: Annette Bening is only 10 years older than Naomi Watts, though it's somewhat justified here as her character, Karen, was only a teen when she had Elizabeth.
5. Film.Notorious 1946: Leopoldine Konstantin was a mere three years older than her on-screen son, Claude Rains.
6. Film.Tales Of An Ancient Empire: Janelle Marra, who plays Rajan, was 31 at the time, only seven years more than Inbar Lavi, playing her daughter Alana. Even worse, Michael Pare plays Oda, father of Aedan, played by Kevin Sorbo, who was born less than a month before him.
7. Film.The Count Of Monte Cristo 2002: Dagmara Domińczyk was twenty six at the film's release. Henry Cavill, who played Albert, the son of her character Mercedes, was nineteen. Meanwhile, Jim Caviezel, who as Dantes turns out to be Albert's true father, was thirty four, which is slightly better. Justified in all cases due to the time frame involved, and the needs of the actors to play their younger selves.
8. Film.Unfaithful The film features a then-37-year-old Diane Lane as a housewife having an affair with a younger man (her infuriated husband is shocked to see how young the guy is and later blasts her for throwing their life away "for a fucking kid!") The "younger" man was played by the then-36 year old Olivier Martinez.
9. Main.Mum Looks Like A Sister: In live-action, Playing Gertrude introduces this effect, because due to age of the actors Mum should be a sister.
10. Recap.Supernatural S 06 E 13 Unforgiven: At one point Dean notes that Debbie Harris "cougar-eyed" Sam, implying Debbie is significantly older than him. Pauline Egan, who plays Debbie, is actually three years younger than Jared Padalecki.
11. Series.Deadwood: Clio King, playing "Aunt" Lou, is only about fourteen years older than Omar Gooding, playing Lou's son, Odell. On the other hand, given the historical setting, it's entirely possible that she gave birth at a very young age. Possible justification
12. Series.Shaka Zulu: Nandi qualifies for this when she ascends to the throne as Queen of Queens (Queen Mother) after Shaka captures the Zulu capital. In fact, her actress Dudu Mkhize is actually younger than Henry Cele. Cele plays her son Shaka
13. Trivia.The Hardy Boys 2020: A literal example: Bea Santos was 30 years old at the time of filming the first season, while playing Gertrude "Trudy" Hardy. James Tupper, who plays Trudy's brother Fenton for the first season, was 55, old enough to be her father, and she's only 7-8 years older than Rohan Campbell, who plays her nephew Frank. While it's implied that Trudy is the younger sibling in this series (unlike the books, where Gertrude is the oldest), dialogue about their childhood indicates that the age gap between her and Fenton isn't meant to be anywhere near that large.

1. Characters.The Witcher 2019 The Nilfgaardian Empire: Bart Edwards is only twelve years older than his series daughter Freya Allan.
2. Creator.Jonathan Rhys Meyers: In The Mortal Instruments: City of Bones, he plays the father of Lily Collins's character, despite only being 11 years older than her.
3. Film.She Hate Me: John Turturro and Monica Bellucci play father and daughter. He is just seven years older than her.
4. Film.The Mummy Tomb Of The Dragon Emperor: Brendan Fraser was 39 at the time of filming. Luke Ford, playing his son, was 26.
5. Recap.Game Of Thrones S 6 E 2 Home: Euron Greyjoy is played by Pilou Asbæk, who's actually a year younger than Gemma Whelan who plays his niece Yara. Uncle/aunt is as egregious as parent; you could have a young uncle...
6. Trivia.Blow: Ray Liotta and Rachael Griffiths play Johnny Depp's character's parents. Depp is older than Griffiths and only slightly younger than Liotta.
7. Trivia.I Live In Fear : Toshiro Mifune plays Minoru Chiaki 's father. Mifune was 35 at the time, and Chiaki was 38.
8. Trivia.KYTV: A running theme in Radio Active is the rivalry between up-and-coming Mike Flex and fading old star Mike Channel. Geoffrey Perkins, who plays the youthful Flex, was actually the oldest member of the cast. Angus Deayton, who is three years younger than Perkins, plays a generation older.
9. Trivia.Mouse 2021: Ahn Jae-wook and Kim Jung-nan (both born in 1971) play the adopted parents of Kwon Hwa-woon (born 1989) and the biological parents of Lee Seung-gi (born 1987). Both mother and father are young, though the age difference is plausible
10. Trivia.The Good Shepherd: Because the film takes place across decades, Matt Damon and Angelina Jolie are only 12 and eight years older, respectively, than Eddie Redmayne, who plays their son.

1. Characters.Mischief Theatre: He portrays the the older butler Perkins in "The Murder at Haversham Manor" with his hair greyed up. Unfortunately, the grey doesn't cover the back of his head.
2. Creator.Angela Lansbury: Due to being Younger Than They Look, Angela was often cast as characters older than she was during The Golden Age of Hollywood.
   "Hollywood made me old before my time."
3. Creator.Wilfrid Brambell: He was often Playing Gertrude and gained a reputation for being old men on screen...
4. Film.Feeding Frenzy: Rich Evans plays the elderly Mr. Plinkett in spite of obviously being a man in his thirties doing an "old man voice." He regularly plays the same role for Red Letter Media web videos.
5. Film.Quills:
   • Geoffrey Rush was 49 years old when the film was released, and played Marquis de Sade up through the latter's death at 74.
   • The 24 year old Joaquin Phoenix plays the 60-odd Abbé de Coulmier — though that might also be considered an Age Lift.
6. Film.Scanners:
   • Patrick McGoohan's character Dr. Ruth was said to have founded a biochemical company in 1942. That would make him somewhat older than McGoohan who was only about 13 or 14 at that time. This is somewhat tempered, though, by McGoohan looking and sounding older than he was at this point in his career. Actor is younger than their character
   • Michael Ironside also plays the older brother of Stephen Lack and is said to have about 4-5 years on him, despite the age difference between the actors actually being the reverse. This is made believable by Ironside's prematurely receding hairline. Actor's ages don't match up exactly, though I don't think 5 years is that notable.
7. Series.The Sweeney: Although John Thaw was only 32 when the show premiered, his character Regan was well into his forties.
8. Series.Still Game: The whole premise of the show is a bunch of 30 and 40 year olds playing 70 and 80 year olds. In fact, Kiernan and Hemphill were asked out by several older women while in character as Jack and Victor.
9. Trivia.Waiting For God: 70-something Diana Trent was played by then 50-year-old Stephanie Cole.

1. Film.Atonement: Romola Garai is three years older than Keira Knightley, who plays her older sister. It's especially notable in the one scene they share together, because Cecilia doesn't seem to have aged at all. Although this actually makes a weird kind of sense: since Briony imagined the entire scene for her book. She thought of herself as much older and more mature after her time as a nurse, but she was still thinking of the Cecelia from her childhood, since in real life they didn't reconcile. But this was mostly just a lucky fluke of having one actress play Cecelia while three played Briony. Justified...?
2. Series.Star Trek Picard: A minor case where Peyton List is two years younger than Harry Treadaway, but her character Narissa is the older sister of his character Narek.
3. Trivia.Once Upon A Time S 4 E 7 The Snow Queen: Pascale Hutton (Gerda) plays the youngest of the sisters but was actually older than Sally Pressman (Helga). Actors' ages don't match up exactly, though I don't think siblings are that notable.

1. Characters.Marvels Spider Man Antagonists: Ben Diskin (who's in his mid-30s) voices the middle-aged character. Additionally, Spencer is the father of Alistair—and Diskin is 9 years younger than Jason Spisak (Alistair's voice actor).
2. Creator.Ray Chase: Has played characters who seem (and sound) noticeably older than him on more than one occasion. Artorius Colbrande, Jason Blood/Etrigan, Keith Flick, and Gendo Ikari are some of the more famous examples.
3. Trivia.Baby Sharks Big Show: Shelby Young (b. 1992) voices Rayna, the mother of William, who is voiced by Luke Youngblood (b. 1986).
4. Trivia.Komi Cant Communicate: In the English dub, Xander Mobus, who voices Masayoshi, is 2 years younger than Amber Lee Connors, who voices his daughter Shoko.
5. Trivia.Little Demon: 13 year old Chrissy is voiced by 39 year old Lucy DeVito, a year older than Aubrey Plaza, who voices Chrissy's mother Laura (and even she's an example, as Plaza's character is four years younger than her).
6. Trivia.The Idolmaster Cinderella Girls: The anime's Producer is undoubtedly an adult in-series. Takeuchi himself was not; he was only seventeen when he played the character.

1. Characters.Ru Pauls Drag Race UK Series 2: Spring chicken Ellie is cast as the positively ancient 'Thot Cotton' (a spoof of EastEnders's venerable Dot Cotton) for the BeastEnders acting challenge, and considering she's the youngest queen in the competition, she does a great job capturing Dot's quavering mannerisms. Later on, in hilariously un-Dot Cotton style, she engages in a massive shagathon all over the pub with special guest star “Mickaaay,” a mannequin version of Danny Dyer’s character Mick Carter, which is all captured on CCTV, to her horror. This is an acting challenge on a reality show; it's not serious.
2. Series.Feud: Inverted — Lange and Sarandon are both older than the people they're playing by at least a decade each. Though Matthew Glave and Salvator Xuereb in their cameos are ten-ish years too young for their cameos as (Dr. Phibes costars) Joseph Cotten and Vincent Price.

1. Characters.Arrowverse Freeland Criminals: Krondon was a mere 35 when the first season aired, yet Tobias was already an established adult villain in flashbacks 30 years ago, meaning he must be at least 50. Subverted when it's revealed later that he takes a serum that keeps him from aging. Justified Older Than They Look
2. Characters.Goldfinger: Varley Thomas was fifty at the time of the filming. And?
3. Creator.Kristen Bell: ...at 26, she was too old to play a high schooler and too young to play the mother of one. So she compromised by providing the voice of Gossip Girl. Talks about perceptions of aging at least.
4. Creator.Laurence Olivier: His film version of Hamlet is the Trope Namer.
5. Film.A Guide To Recognizing Your Saints: There's only five years between Rosario Dawson and Melonie Diaz, who play the same character fifteen years apart. This is due to Diaz playing a teenager, while Dawson playing someone a couple of years older than she actually is. Same...person example?
6. Film.Road House 1989: Wade is presented as a mentor/surrogate father figure to Dalton, despite their actors only being 8 years apart in age. Of course, as noted above, Sam Elliott had a strong case of Younger Than They Look. You can have a mentor/father figure 8 years older than you; the example doesn't specify if Wade is supposed to be significantly older
7. Series.Upstart Crow: Will asks Condell to play Gertrude in Hamlet and the actor immediately claims that he's too young for the role but will give it a try, anyway. Reference to the trope namer and aging but otherwise not clear