"There is very little you can beat into a child, but no limit to what you can hug out of it."
Astrid Lindgren (1907-2002) was a Swedish author of children's books. Her books have been translated into 85 languages, published in more than a hundred countries and sold more than 145 million copies. She has written dozens of books; some of the most famous ones are Pippi Longstocking, Mio, My Mio, and Karlsson on the Roof. They verge from the relatively mundane (The Children of Noisy Village) to children's detective stories (the Bill Bergson series) to straight-out fantasy (Ronja the Robber's Daughter, The Brothers Lionheart) A good chunk of her books have been turned into movies or TV-series (most of the movies are edited from TV-footage though).She has an asteroid named for her; on learning this, she commented that henceforth they could call her "Asteroid Lindgren". She also did narrated readings of many of her books for Swedish television and radio.She was Sweden's very own Dear Grandmother.
Action Girl: Any girl protagonist of Lindgren has a good chance of having at least some elements of this, especially in the books with fantastic elements. Pippi and Ronja are the clearest examples, but there are many others.
A Girl And Her Dog: Tjorven of Vi På Saltkråkan ("Seacrow Island") and her huge St. Bernard dog, Båtsmann. While several children in other Lindgren stories have pets (most often dogs) and are very close to them, Tjorven and her dog are absolutely inseparable and their friendship very central to their story.
Perhaps most straight-up example is Lotta, the Breakout Character of the Children of Troublemaker Street book, who is a real pain in the neck to her older brother and sister more often than she's not, and who completely takes over as the star of the the sequel and subsequent short stories while the older siblings only get a few cameo appearances.
Lisabet, the younger sister of Madicken/Mischievous Meg, also has notable traits of an Annoying Younger Sibling, though in this case the sisters are much more a double act and tend to get in trouble together. Not as much of a Breakout Character as Lotta, as Madicken herself remains the viewpoint character, but gets A Day in the Limelight fairly often.
Lillebror of the Karlsson on the Roof stories is definitely one in the eyes of his older siblings, though he's also the viewpoint character for the books, and compared to Karlsson he's downright angelic.
Author Tract: And Author Avatar, at the same time: Pomperipossa in Monismania is about a writer of childrens' books who lives in a country that, while mostly a fairish place to live, has quirks in the tax system that lead to the marginal tax rate being 102% for Pomperipossa. It was written in reaction to Lindgren finding out that her marginal tax rate was... 102%, as an unintended consequence of the combination of self-employment and a high income. Some Anvils Need to Be Dropped may apply; the story lead to a fairly intensive debate regarding taxes, and may even have been a decisive factor in the Social Democrats losing the elections to the Riksdag that year, for the first time in 40 years.
Bittersweet Ending: Several of her short stories have these; in a few of them one or more of the protagonists either die or are heavily implied to die, but usually life for those who are left behind goes on, and sometimes even gets better:
In Most Beloved Sister, seven year old Barbara feels unloved and unwanted at home after the birth of her baby brother, and has magical adventures with her "secret twin sister" Lalla-Lee, who may or may not be imaginary — at the end of the story, Lalla-Lee dies and the magical world is closed off, but Barbara comes to the realization that her parents do still love her, and she gets the puppy she's always wanted.
In The Red Bird, orphans Matthew and Anna live a harsh life, but frequently escape to a secret place that, once again, may or may not be imaginary; a paradise where they're taken care of and loved. At the end, they choose to stay in this paradise rather than return to their dreary lives, which pretty heavily implies that they die.
My Nightingale is Singing features the recently-orphaned Maria, who throughout the story takes comfort and inspiration from the words of a story she hears — "my linden plays, my nightingale is singing." Though she effectively dies at the end of the story, her spirit lives on as a playing linden tree, which with its music does bring her friends at the poorhouse the beauty and joy she wanted to give them.
Changeling Fantasy: Mio's father was not a scoundrel, he had to go away and rule his realm... and search for his son, whose mother died in childbirth, all over the world for years and years to bring him home as the prince of the Land Far Away.
Children Are Cruel: Several examples, though there's seldom any real malice behind their cruelty.
Dawson Casting: The actor playing the oldest brother in the movie version of The Brothers Lionheart is significantly older than his character was in the book. Though it's never actually mentioned how old he is in the movie, so this might just be a case of Age Lift. It also does pay off in the end, since this makes him a credible leader of La Résistance.
Inverted and played with with the live-action Karlsson-on-the-roof, who is played by a child actor and overdubbed with the voice of an adult man, further underlining the Vague Age of the character.
Frothy Mugs of Water: Averted. Alcohol is rare in Lindgren's stories, but she doesn't shy away from it or from descibing its destructive effects either. For example, the family in Emil of Lönneberga is mostly sober, since the father is a deacon, but the father is clearly drunk after having been bought beer by a neighbour at the fair in Vimmerby, the farmhands drink vodka and brawl at an auction, and Emil's own experiences with his mother's cherry wine dregs take up an entire story arc.
The Gay Nineties: While not *exactly* the same (most of the stories would take place in the early 20th century) the depiction of rural Sweden in eg. Emil of Lönneberga and Children of the Noisy Village has much in common with this trope.
Great Gazoo: Karlsson from the eponymous book. Not really powerful as Great Gazoos go, but still qualifies.
Heel-Face Turn: Not surprisingly, happens with Nicke, the kindest of the villains in Bill Bergson and the Great White Rose Rescue. It looks like it's going to be a case of Redemption Equals Death, as he is shot and wounded by his former boss, but it turns out the gunshot wasn't fatal, and he survives.
Jerk with a Heart of Gold: Karlsson-on-the-roof. He's selfish, he's vain, he sulks whenever he doesn't get his way, he has no qualms about lying, cheating or stealing. But he never means any real harm, and he does get some real Pet the Dog moments (sometimes literally, as he's shown as being quite kind to dogs).
Emil's father also qualifies as this. He's an insufferable cheapskate and overly temperamental, but at the end of the day he's really quite soft-hearted.
Leaning on the Fourth Wall: In the otherwise fairly realistic Bill Bergson and the White Rose Rescue, Bill and Anders at one point half-jokingly philosophize about the possibility of them being fictional characters in a book, and how they can't be sure they aren't, because they wouldn't have been written with the knowledge that they are.
Like Brother and Sister: Ronja and Birk (possible subversion, in that they decide to be brother and sister, and call each other that on several occasions, but there are hints that the relationship could grow to be something more in later years. Birk's mother is certainly convinced of that, and none too pleased about it.)
Literary Agent Hypothesis: The Emil books are supposedly based on the writings of Emil's mother, who meticulously wrote down all of Emil's pranks in blue notebooks. Sometimes Lindgren directly quotes from these books either before or after telling about the incident in greater detail, often adding her own thoughts about them and at one point criticizing Emil's mother for being too inaccurate and leaving out important details.
Mafia Princess: Ronja has some of these characteristics. When she finds out what a robber actually DOES she runs away from home.
Mordor: The dark land ruled by Kato in Mio and Karmanjaka in "The Brothers Lionheart".
Maybe Magic, Maybe Mundane: Several of the stories, especially the short stories, leave it fairly ambiguous whether the fantastic things are actually happening or whether it's all just a product of the child protagonist's imagination.
Most Writers Are Adults: Jonatan Lionheart is a prime example of this trope. He's aged up for the movie and it makes much more sense that way.
Mundane Afterlife: The Brothers Lionheart has an odd example. Nangijala is "The land of stories and campfires" but is generally pretty normal. Then it turns out that there may be another afterlife after that.
Noodle Incident: The author "has been sworn to secrecy" about what Emil did on the Third of November, so she teases the readers about it at every opportunity. That was the time the villagers took up a collection to send Emil to America.
Our Dragons Are Different: Katla is a big honking lizard, scared of loud noises and breathes fire that will kill or paralyze you.
The titular dragon of The Dragon With The Red Eyes is a tiny baby dragon unexpectedly born from a pig. This is never explained, nor is the baby dragon, who is quite mischievous and troublesome, but also cute and loveable in his own way.
Precision F-Strike: In Emil of Lönneberga, the farmhand Alfred tries for a long time to come up with a way to tell the maid Lina that he is not interested in marrying her, keeps stalling because he wants to say it in "A somewhat nice way" in order to not hurt her feelings. Ultimately, he tells her; "You know Lina, that engagement we have been talking about? I really think we should screw that." The narrator then explains to the reader that "I do not want to teach you any bad words, but that was really the best poor Alfred could come up with."
Later on, Emil goes through a number of really severe swearwords with his little sister, but does so only to teach her things she must absolutely never say.
Pig Latin: The Bill Bergson books invented Rövarspråket, which has become the Swedish equivalent of Pig Latin and is still in fairly wide use 60 years later.
¡Three Amigos!: Bill, Anders and Eva-Lotta in the Bill Bergson books. They can also be seen as a Freudian Trio, with Bill as the Superego, Eva-Lotta as the Ego and Anders as the Id.
Tortured Monster: The villain of Mio, my Mio has a heart of stone, seemingly literally. He is in constant agony from its chafing in his chest, and begs to be killed at the end.
Vague Age: Karlsson. Is he a child or an adult, or simply an ageless creature of fantasy? When asked, he only says that he's "a man in his prime" but doesn't elaborate further.