Practically Different Generations / Live-Action Films

• Josh Framm from Air Bud is twelve years old while his younger sister Andrea is around one to two years old. He later gets a half-brother named Noah who is a whopping twenty years younger, give or take a few.
• American History X: Ally Vinnyard, who is only a Living Prop in the film, is about seven years old. Her siblings are all much older than her; with Derek being in his early to mid-twenties, Davina being in her late teens to early twenties, and Danny being in his mid- to late teens.
• In Avatar: The Way of Water, Tonowari and Ronal's two eldest children, Aonung and Tsireya, appear to be teenagers, while their mother is currently pregnant with a third child.
• Avengers: Age of Ultron: Clint Barton has two children, Cooper (then aged 12) and Lila (then aged 10), and his wife Laura is expecting their third child, Nathaniel. By the time of Hawkeye (2021), 9 years later, the Barton children are 16, 14 and 5 respectively due to losing five years during the Blip.
• Baby Of The Bride: Margret already has four adult children from her previous marriage by the time she and her new husband John have their son Sam.
• In The Bachelor and the Bobby-Soxer, Myrna Loy is the older sister to Shirley Temple, despite a 22-year age gap. The reason for that decision is probably because they're in a Love Triangle with Cary Grant and having a mother and daughter in a triangle would be too much Squick.
• Back to the Future: Marty McFly's mother Lorraine, who is 17 in 1955 and the eldest of five siblings, is 16 years older than her youngest brother Joey as well as another sibling who isn't born yet.
• Black Panther (2018): T'Challa's exact age is not given, but he is likely in his early to mid-thirties. (His actor, Chadwick Boseman, was in his early 40s at the time of filming, though a deleted scene shows T'Challa as a child in 1992, which would make him at least half a decade younger.) His younger sister Shuri is 16 years old.
• Blair Witch: James Donahue is revealed to be the younger brother of Heather from the original The Blair Witch Project. The events of the 2016 film takes place twenty years after the events of the first film when Heather was 22. James is 24 in the film's current timeline, thus making him 18-20 years younger than Heather.
• In Cheaper by the Dozen (2003), Nora Baker, the eldest of the twelve children, is a 22-year-old adult who has left home and lives with her boyfriend. The youngest Baker children, twins Kyle and Nigel, are about five or six years old (their dad Tom finally got a vasectomy after the twins were born). All the other kids fall somewhere in between the nearly two-decade age gap.
• In Crazy, Stupid, Love, a large age gap sets up a plot twist. Jacob, who is in his late twenties, knows that Cal has two children, a thirteen-year-old son and a younger daughter. He does not find out that Cal also has a much older daughter, Hannah — the woman Jacob is dating — until much later.
• In Curly Top, seven-year-old Shirley Temple and nineteen-year-old Rochelle Hudson portray sisters.
• In Disenchanted (2022), Giselle and Robert's infant daughter Sofia has just turned one, while Morgan, Robert's daughter from his first marriage and Giselle's Happily Adopted stepdaughter is sixteen, putting the sisters at around fifteen years apart.
• Dune (2021) and Dune: Part Two: Paul is around fifteen years old, if not slightly older ^note his age isn't specified in the films and Timothée Chalamet was in his twenties at the time of filming; in the book he's stated to be fifteen. Using his powers of foresight, Paul realizes his mother is several weeks pregnant with her second child, meaning his future sibling will be over a decade younger than him, potentially bordering on two decades younger. Due to the age of their actors Rabban is also about two decades older than his brother Feyd Rautha.
• Elf: Buddy is a man in his early thirties, while his paternal half-brother Michael is 12. The fairly large age gap was the result of their father Walter unknowingly impregnating his girlfriend during college, and then marrying a different woman several years later.
• Enola Holmes is a sixteen-year-old girl, while her brothers are middle-aged career men. This is plot-relevant, as because they have been away from home for so long, they are initially not interested in acting as close-knit guardian figures and would prefer to ship her Off to Boarding School.
• Father of the Bride (1991): In the first movie, Annie Banks is twenty-two years old. Her younger brother Matty is eight years old. By the time their younger sister Megan is born on the same night as Annie's son in the sequel, Matty is twelve years old.
• Father of the Bride (2022): Fresh law school grad Adan has a baby brother due to his father remarrying a woman his age.
• Five Nights at Freddy's (2023): Abby is Mike's younger sister, but whereas Mike seems to be somewhere in his twenties, Abby isn't even 10. He's also her legal guardian and takes her with him on his night job because he cannot afford a babysitter.
• Halloween: In the timelines where Laurie and Michael are siblings, their sister Judith is about 13 years older than Laurie.
• Halloween (2007): Judith and Michael Myers are 16 and 10 years older than their younger sister Laurie Strode/Angel Myers. Shortly after Michael killed Judith, Judith's boyfriend, and their stepfather Ronnie, their mother Deborah gave the infant Angel up for adoption and committed suicide. Angel's new adopted parents renamed her Laurie and were never informed of her tragic past. Thus she has no knowledge of her biological siblings until an escaped Michael comes charging into her life.
• In The Harder They Fall (2021), this is a result of the main plot's reveal; everyone knows Rufus murdered Nat's parents when Nat was ten years old, but he finds out why at the climax. Rufus' father used to be an abusive drunk, and he murdered his wife in a rage when Rufus was ten years old. When Rufus found him years later to get revenge, he was sober and kind, with a second wife and son.
• Here Comes the Boom: Despite being in their late forties, Marty Streb's wife Mollie is pregnant with another child. That unborn child was mentioned in a passing line to be 22 years younger than their unseen older brother.
• Hocus Pocus has a moderate example with Max, in his mid teens, and his eight-year-old sister Dani. There's also a similar age gap in the prologue between the teenaged Thackeray Binx and his doomed little sister Emily. If the age differences between the Sanderson sisters are the same as between their actresses, then this trope also applies to them, although it's less evident because they're all adults: Bette Midler (Winifred) is twelve years older than Kathy Najimy (Mary), and Sarah Jessica Parker (Sarah) is eight years younger than Najimy and twenty years younger than Midler. (This is Jossed by Hocus Pocus 2, however, which flashes back to show Winifred and Mary as teens and Sarah as a preteen together.)
• Hollow In The Land: Brandon is stated to be 17 years old, while his older sister (and legal guardian after their father was incarcerated for murder) Allison seems to be in her thirties. There is enough of an age difference between them that Allison is dating the mother of Brandon's girlfriend.
• Holy Matrimony: Peter appears to be in his early 30s, while his younger brother Zeke is explicitly 12.
• Honey, I Blew Up the Kid: Adam Szalinski is a toddler. His sister Amy is in college and his brother Nick is in high school.
• Johnny Kapahala Back On Board: Subverted because it's step-family, but when Johnny's grandfather gets married to a younger woman (she's around the same age as Johnny's dad), Johnny gets a new "uncle" younger than him.
• Joker (2019): Arthur Fleck believes himself to the illegitimate son of Thomas Wayne. If this is true, then Fleck (implied to be in his early thirties) would be over 20 years older than his half-brother Bruce (who is only 10). Subverted, as it turns that Fleck's mother Penny was a Stalker with a Crush to the older Wayne, which got her fired from Wayne Enterprises. Penny then deluded herself into thinking that Wayne was Fleck's father.
• In Juno, the titular Juno is sixteen while her paternal half-sister Liberty Belle is five. It's implied near the start of the film that Juno's maternal half-siblings are younger than not just Juno, but Liberty Belle too.
• Kicking & Screaming: The main character Phil Weston's half-brother Bucky is born on the same day as his son Sam. Thus, the audience is treated to ridiculous scenarios such as Phil's 10 year old half-brother repeatedly calling him "bro" and him asserting himself over Phil's son on the grounds that he's his uncle.
• In Labyrinth, Sarah is sixteen years old while her younger half-brother Toby is still a baby and has only just started to toddle. As a result, Sarah is often tasked with caring for him while her father and stepmother are out, which she resents. However, when Toby is kidnapped by goblins, Sarah's Big Sister Instinct kicks in and she sets out to rescue him.
• Lights Out (2016): Their ages aren't specified, but Rebecca is probably somewhere in her late twenties to early thirties (her actress, Teresa Palmer, was 29 at the time of filming). Her maternal half-brother, Martin, on the other hand, is maybe around 8 to 10 years old (his actor, Gabriel Bateman, was 10). Through most of the film, Rebecca is battling with their mutual mother for custody over Martin.
• License to Drive: The Andersons have two 16-year-olds, an 11-year-old, and two newborn babies.
• The Messengers: Jessica is a girl in her late teens, with her younger brother Ben a toddler who still uses a crib.
• Music (2021): While it's never specified how old Kazu and her half-sister Music are, Kazu is presumably somewhere in her early to mid-thirties (her actress, Kate Hudson, was 38 at the time of filming) while Music is presumably somewhere in her early teens (her actress, Maddie Ziegler, was 14). Kazu ends up having to take care of Music after their grandmother suddenly dies from a stroke.
• My Girl 2: Vada is thirteen when her half-brother is born.
• Napoleon Dynamite: Napoleon is 16 years old, while his Manchild of an older brother Kip is 32. Evidently, large sibling age gaps are a tradition in Napoleon's family, as the brothers' uncle Rico seems to be only in his 40s, and thus is probably no more than 8 to 10 years older than Kip.
• In The Northman, Amleth and Gunnar are maternal half-brothers and have decades between them. Gunnar's older paternal half-brother Thorir is younger than Amleth, but still decades older than Gunnar, too. Gunnar looks to be around 10 years old; at the start of the film Amleth is 10 while Thorir is a baby before the story skips ahead about two decades, which would make Amleth around 30 years older and Thorir about 20 years older than their little brother.^note in real life, Amleth's actor Alexander Skarsgård was in his mid-40s, though he could pass for younger and it's implied Amleth is supposed to be in his thirties Amleth especially could easily be Gunnar's father rather than his brother. Gunnar doesn't even know Amleth is his brother, as he was assumed to have died as a child long before Gunnar was born. Despite them being practically strangers and Amleth despising Gunnar's father, Amleth still protects Gunnar from harm and doesn't target him in his revenge plot at least until he's forced to kill him in self-defense.
• Overlord (2018): The French La Résistance fighter Chloe is in her early twenties. Her younger brother Paul seems to be at least 8 years old. This gives the two a minimum of 12 to 15 year age difference.
• The Pacifier: There is over a decade in age between the two oldest Plummer children and their two youngest siblings.
• Parenthood: Helen's daughter Julie is in high school and her son Garry has just started puberty. Towards the end of the film, she starts dating Garry's science teacher, George, and discovers that Julie's pregnant. The movie ends with Helen giving birth to George's daughter, who is just a few months younger than Julie's baby.
• The Proposition: Mikey, the youngest of the Burns brothers (a family-led gang of bushrangers that prowl the outback of colonial Australia), is 14 years old. His older brothers, Arthur and Charlie, are likely in their mid-twenties to early thirties.
• Quints: Jamie is fourteen years old when her mother gives birth to quintuplets.
• Rain Man: Raymond Babbitt was in his late teens when his younger brother Charlie was born. Because Raymond was sent away to a group home at the age of 18, Charlie didn't even know of his existence until their father died and he learned that the inheritance was being sent to the group home where Raymond lived.
• The Santa Clause: Charlie Calvin is about a decade older than his half-sister Lucy from his mother's second marriage. He's an adult by the time his half-brother Buddy from his father's second marriage is born at the end of the third film and by the time of the Sequel Series, he has another even younger half-sister Sandra.
• Saving Face: Wilhelmina Pang is twenty-nine years old when she finds out her forty-eight-year-old mother Gao is pregnant again.
• Sharknado: In the first movie, Finn and April are a divorced couple with an adult son and a teenage daughter. By the third movie, they're back together and have a newborn son.
• In Sorcerers, Ivan (In-Universe age unspecified, the actor being twenty-nine at the time) has a little sister Nina (age unspecified, the actress being nine). At first, she seems like an Annoying Younger Sibling, insisting she'll accompany him for his romantic evening with his fiancée and later sneaking after him when he goes to said fiancée's rescue. However, she is very quick-thinking, while her brother is badly affected by Love Makes You Stupid, and she ends up helping him a lot.
• In Stand by Me and the original novella that inspired it, Gordie and his late older brother Denny are separated by a ten-year age gap. Their relationship is portrayed as distant in the book (the age gap renders Denny "just a guy"), but in the movie, Denny is painted as having been a kindly older brother who encouraged Gordie's writing. Gordie's parents (noted in the narrative as old enough to be his grandparents) have ignored him since Denny's death. It's given more focus in the novella that Denny was a miracle baby for his parents, who had believed themselves infertile, so he was the object of Parental Favoritism; Gordie, on the other hand, was not planned and is The Unfavorite.
• Super Mario Bros. (1993): In contrast to the video games (where they're fraternal twins), Mario's middle-aged while Luigi appears to be in his early 20s—in fact, it's stated that Mario was the one who raised Luigi after their parents died (and Luigi was apparently too young to really remember their parents, as he claims that Mario's the only parental figure he really remembers).
• That Darn Cat!: Patti is in high school. Her older sister Ingrid is an adult in her late twenties or early thirties.
• Thor: Ragnarok: Hela's age is not given in the films, but she is considerably older than her 1,500-year-old brother Thor. This can be inferred from the facts that he (along with most of Asgard) was unaware of her existence prior to the events of Thor Ragnarok, and that Hela was old enough to be a powerhouse in her own right before Thor and Loki's births.
• This Is 40: Both Pete and Debbie's fathers have remarried and sired children who are much younger than them. In Pete's case, his half-brothers are actually younger than his and Debbie's own children.
• At beginning of War for the Planet of the Apes, Ceaser's oldest son Blue Eyes is a married young adult and his youngest son Cornelius is a toddler. After the deaths of his entire family, Cornelius' widowed sister-in-law Lake adopts him.
• Totally Killer: Due to the changes that 17-year-old Jamie causes in the timeline, her parents now hooked up in high school, causing her to have a 34-year-old brother when she returns to the present.
• What to Expect When You're Expecting: Skyler and Ramsay's twins are young enough to be their older brother Gary's children, and are indeed the same age as— and share a birthday with — their nephew.
• Wild Things: A plot point that was left on the cutting room floor revealed that Sandra Van Ryan's late father, a notorious philanderer, is also Suzie's father. This makes Suzie and Sandra half-sisters, even though Sandra is a woman roughly in her 40s and Suzie is a teenager (played by a 20-something actress). Being a Van Ryan bastard also gives Suzie more plausible motivation for feeling entitled to a considerable part of the Van Ryan family fortune.
• The tendency of the prequel X-Men films to set each film a decade apart leads to this with the Summers brothers. Havok is older and is a teenager in X-Men: First Class in the '60s, while Cyclops is a similar age when introduced in X-Men: Apocalypse in the '80s.
• In You've Got Mail, Tom Hanks's character Joe has a 4-year-old half-brother. He also has an 11-year-old aunt, his grandfather's daughter with a younger woman.