The content of this article is derived from notes and drafts of the Harry Potter books/films/games that were cut before being released. As such, the contents of the article may or may not be considered canonical.
In 1992, in around his five-hundreth Deathday, the ghost of Sir Nicholas de Mimsy-Porpington authored a ballad titled "The Ballad of Nearly Headless Nick" explaining why he was sentenced to beheading and how his head had (nearly) come off in a botched execution:
It was a mistake any wizard could make,
Who was tired and caught on the hop,
One piffling error, and then, to my terror,
I found myself facing the chop.
Alas for the eve when I met Lady Grieve,
A-strolling the park in the dusk!
She was of the belief I could straighten her teeth,
Next moment she'd sprouted a tusk.
I cried through the night that I'd soon put her right,
But the process of justice was lax;
They'd brought out the block, though they'd mislaid the rock,