- Draco's last name was originally Spungen.
- Hermione's original surname was Puckle, but it didn't suit her.
- In early drafts, James and Lily Potter's betrayer was a Muggle. As the story evolved, Peter Pettigrew became the traitor, and the horrible Muggle disappeared.
- In the original draft, the Ford Anglia crashed into the Black Lake instead of the Whomping Willow, and Harry and Ron met the merpeople who live there.
- This ballad originally appeared in the manuscript. It was cut in the editing process but appeared on J.K. Rowling's official website. In 1992, around his five hundredth 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,
Where they usually sharpened the axe.
Next morning at dawn, with a face most forlorn,
The priest said to try not to cry,
"You can come just like that; no, you won't need a hat,"
And I knew that my end must be nigh.
The man in the mask who would have the sad task,
Of cleaving my head from my neck,
Said "Nick, if you please, will you get to your knees,"
And I turned to a gibbering wreck.
"This may sting a bit," said the cack-handed twit,
As he swung the axe up in the air,
But oh the blunt blade! No difference it made,
My head was still definitely there.
The axeman he hacked and he whacked and he thwacked,
"Won't be too long," he assured me,
But quick it was not, and the bone-headed clot,
Took forty-five goes 'til he floored me.
And so I was dead, but my faithful old head,
It never saw fit to desert me,
It still lingers on, that's the end of my song,
And now, please applaud, or you'll hurt me.
- In a handwritten planning note, Professor Aurora Sinistra was recorded as "Aurelia Sinistra." The name Sinistra also appears next to the list of Defense Against the Dark Arts professors, but it is not known if it is the same Sinistra.
- Rowling also considered the first names Pi and Digit for Septima Vector, the Arithmancy professor.
- There was originally a professor named Mopsus who taught Divination.
- Enid Pettigrew was considered for two different subjects: a possible Defense Against the Dark Arts professor in the fourth book or as the Divination professor. Ultimately, those roles went to Alastor Moody and Sybill Trelawney, respectively.
- Mafalda was supposed to convey certain information about the Death Eaters to Harry, Hermione, and Ron. She is three years younger than the trio and was Sorted into Slytherin House. She is the daughter of Mrs. Weasley’s second cousin who’s an accountant and is highly gifted academically, becoming a real show-off to her fellow peers. Ultimately, the character Rita Skeeter took Mafalda’s place in the series.
- The Order of the Phoenix was originally the name of the student group Hermione and Harry started, not Dumbledore's Army. Dumbledore's Army was originally the name of the adults-only Death Eater resistance group, not the Order of the Phoenix.
- Two other names were also considered for the Defense Against the Dark Arts professor: Mylor Silvanus and Oakden Hobday (not Umbridge).
- Umbridge's first name was originally Elvira rather than Dolores.
- Grawp was originally Hagrid's cousin.
- Arthur Weasley was originally planned to die.
- In an early draft, the person visiting Bode at St. Mungo's on Christmas Eve was the Death Eater Macnair.
- Professor Trocar, a subjectless vampire teacher, appeared on one of J.K. Rowling’s earliest lists of Hogwarts staff. A rather clever name for a vampire, a trocar is by definition a sharply pointed shaft inserted into arteries or cavities to extract bodily fluids. Trocar disappears fairly early on in her notes, and despite fan rumors labeling Snape a vampire, Rowling confirms that he is not a revamped Trocar.
- J.K. Rowling stated that she had always planned for Hermione to have a younger sister. However, Rowling felt it was too late to introduce her since she had not made an appearance by Order of the Phoenix.