Almost every single hero or heroine in literature is an only child. Only children are clearly the BEST :)

[Very]

It's astonishing!

Harry Potter
...and Hermione
...and Draco
...and Neville
...and Luna
...and Pansy, Theo, Luna, Blaise, ....and Remus, Severus, Delphini (spoiler alert!)
and that's just JK Rowling.

There's also everyone from Dickens. Milly Molly Mandy. Pippi Longstocking. Most of the children from Roald Dahl - Charlie, Danny, James, Matilda, etc. Pretty much every Disney princess ever - okay, not ideal childhoods but still proof that NEARLY EVERY INTERESTING CHARACTER IN LITERATURE IS AN ONLY CHILD!

Yay

Oh there's just no need, is there, no matter how many DCs anyone has, others should just keep their beak's out!

I know it's not the place, but in response to what you've just said Poor Richard some of the most upsetting and/or infuriating comments I've received have actually been from parents of only children, sometimes subtly, other times not e.g. -

commenting on the over population of the planet whilst making the point that their family doesn't use up more than their fair share of the world's resources;

mentioning how their family can afford to go on the best (in their opinion) holidays and eat out as often as they like in the best restaurants, because they can afford it with only one child

how they have plenty of time to chill and relax because they only have one child.

It's not even in response to me asking them which restaurants they go to, or how expensive/exclusive their holidays are, or mentioning that I'm tired/asking them about their energy levels.

Great Expectations - Pip was raised by his older sister but effectively was like an only child. Estella was an only child (orphan)

HP series had the Weasley family playing rather a large role.

Good point dreichuplands - they were seen as as fun, down to earth, supportive and loving.

Hermione in the early days at least, didn't do much for the image of only children.

I'm not a HP, fan, but also the fat, spoilt only child with whom Harry spent his early years, ditto!

You can add Sarah Crewe and Mary Lennox, though admittedly Mary needed to be taught basic manners from kids with siblings. You could argue that some books deliberately play on the stereotype - Mary's parents have only one child and have no interest in children, selfishly pursuing a life of parties while ignoring their child and giving her everything materially she could wish for in order to keep her quiet.

I think I’ve yet to watch an Anime (bar pokemon) where the children have parents...

There are a heck of a lot car crashes in Japan...

The most important Disney Princesses in my DD's eyes are Elsa - she has a sister and Ariel who has a lot of sisters and Elena of Avalor (on Disney junior channel -a series) has a sister!