You’ve probably noticed that Hogwarts is ever-so-slightly bigger than your average one-bedroom bungalow.
Moaning Myrtle in her bathroom from the Chamber of Secrets

And yet, although the castle was host to thousands of oddities in every nook and cranny, many of its strangest incidents seemed to end up in one particular, slightly smelly place.

Hermione turned into a cat

A quick bathroom break to spruce yourself up is hardly out of the ordinary. But for Hermione, a makeover in a toilet cubicle ended up getting hairy, due to a slightly misjudged glug of Polyjuice Potion. Thankfully, the resident bathroom ghost, Moaning Myrtle, was on hand to cheer her up.

Her face was covered in black fur. Her eyes had gone yellow and there were long pointed ears poking through her hair.
‘It was a c-cat hair!’ she howled. ‘M-Millicent Bulstrode m-must have a cat! And the P-Potion isn’t supposed to be used for animal transformations!’
‘Uh oh,’ said Ron.
‘You’ll be teased something dreadful,’ said Myrtle happily.
Harry Potter and Chamber of Secrets

An illustration of Hermione after taking Polyjuice Potion of a cat

The Chamber of Secrets opened

The Chamber of Secrets: officially the worst thing you can find in your bathroom, save perhaps for a particularly bad patch of mildew. Nonetheless, Harry spent pretty much his entire second year at Hogwarts trying to find it.

‘What d’you want me to do?’ said Lockhart weakly. ‘I don’t know where the Chamber of Secrets is. There’s nothing I can do.’
‘You’re in luck,’ said Harry, forcing Lockhart to his feet at wandpoint. ‘We think we know where it is. And what’s inside it. Let’s go.’
They marched Lockhart out of his office and down the nearest stairs, along the dark corridor where the messages shone on the wall, to the door of Moaning Myrtle’s bathroom.
Harry Potter and the Chamber of Secrets

Harry looking inside the Chamber of Secrets

TROLL!

As it is for many teenage boys, the girls’ bathrooms of Hogwarts are an intimidating place. This goes right back to Harry’s first year, when he and Ron rescued their new friend Hermione from a slightly troublesome troll.

‘Oh, no,’ said Ron, pale as the Bloody Baron.
‘It’s the girls’ toilets!’ Harry gasped.
‘Hermione!’ they said together.
It was the last thing they wanted to do, but what choice did they have? Wheeling around they sprinted back to the door and turned the key, fumbling in their panic – Harry pulled the door open – they ran inside. Hermione Granger was shrinking against the wall opposite, looking as if she was about to faint. The troll was advancing on her, knocking the sinks off the walls as it went.
Harry Potter and the Philosopher’s Stone

The troll in the girls bathroom

Harry took a bath with an egg

The Triwizard Tournament was a great source of stress for Harry, especially when it came to sussing out the mystery of a screeching, golden egg. But what better way to figure out the riddle of a magical object than a nice, relaxing bath? Isn’t that right, Myrtle? Wait – what was Myrtle doing there?

‘I’d try putting it in the water, if I were you.’
Harry had swallowed a considerable amount of bubbles in shock.
He stood up, spluttering, and saw the ghost of a very glum-looking girl sitting cross-legged on top of one of the taps. It was Moaning Myrtle, who was usually to be heard sobbing in the S-bend of a toilet three floors below.
‘Myrtle!’ Harry said in outrage. ‘I’m – I’m not wearing anything!’
Harry Potter and the Goblet of Fire

Harry in the prefects bathroom

Harry nearly murdered Draco

Oh, how far away those days of secretly brewing Polyjuice Potion must have seemed to Harry when one moment in a Hogwarts bathroom turned bloody. Enamoured with the new spells learnt from the Half-Blood Prince, a run-in with Malfoy seemed like the opportune time to try one of them out. Oh, how wrong Harry was.

‘SECTUMSEMPRA!’ bellowed Harry from the floor, waving his wand wildly.
Blood spurted from Malfoy’s face and chest as though he had been slashed with an invisible sword. He staggered backwards and collapsed on to the waterlogged floor with a great splash, his wand falling from his limp right hand.
‘No –’ gasped Harry.
Slipping and staggering, Harry got to his feet and plunged towards Malfoy, whose face was now shining scarlet, his white hands scrabbling at his blood-soaked chest.
‘No – I didn’t –’
Harry did not know what he was saying; he fell to his knees beside Malfoy, who was shaking uncontrollably in a pool of his own blood. Moaning Myrtle let out a deafening scream. ‘MURDER! MURDER IN THE BATHROOM! MURDER!’
Harry Potter and the Half-Blood Prince

Draco lying on the bathroom floor after Harry's curse
Harry Potter to Fantastic Beasts
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