|"I show not your face but your heart's desire."|
A burglar alarm is a Muggle electronic device used to detect home intruders. Wizards can easily disable a burglar alarm by a casting a Freezing Charm upon it, as demonstrated by Horace Slughorn, when he disabled the alarm of a house in Budleigh Babberton in the summer of 1996.
- Harry Potter and the Half-Blood Prince (First mentioned)
- Fantastic Beasts and Where to Find Them (film) (First appearance)