•Why it earns a slot
Why it earns a slot: Twain built the American boyhood myth out of a graveyard murder, a blood oath, and a killer who ate candle wax and bat claws rather than die easy, and none of it reads like a children's book once you're actually in the text.
Tom Sawyer turns whitewashing into a scam, then watches a murder from behind a gravestone and has to choose between silence and the truth.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.