Magic Detectors are devices used to detect the magic used by Fairies. These devices are usually deployed by Mr. Crocker in his never-ending hunt to reveal the magical creatures to the world. Crocker's inventions are typically crude, unwieldy, and sometimes dangerous, though, thankfully they are mostly only dangerous to Crocker's health.
- Main article: Transparents!
In his first appearance in the series, Crocker uses a "Fairy Finder" device to detect that the two beings posing as Timmy's parents are really Cosmo and Wanda. He attempts to employ a variety of traps to get them to reveal themselves, only to severely injure himself each time. It is also mentioned that a patent is pending on the device.
- Main article: Abra-Catastrophe!
Mr. Crocker was hunting fairies in his Unsuspecting Van when he noticed a large swarm of magic coming from Timmy Turner's house. His magic detector detected the Fairy-versary Muffin in Timmy's clutches, and he set his mission on obtaining the muffin from him to prove the existence of Fairy Godparents.
The Masked Magician
- Main article: The Masked Magician
Mr. Crocker also had a small, handheld Magic Detector device when he visited the Turner's block party magic show. At first he thought Mr. Bickles was really using magic when his magic detector sensed something in the area, although it was really Cosmo and Wanda.
Dread N' Breakfast
- Main article: Dread 'N' Breakfast
When Crocker paid to spend a night at the Turner's bed and breakfast house, he wore a magic detecting device with many butterfly nets on it. Timmy wisely does not use any magic in his presence, keeping Cosmo and Wanda hidden until the very end when he was able to hide them amongst an army of reanimated sock puppets. Crocker's magic device was destroyed and he quickly fled the scene.