Derrick, A.K.A. Experiment 566, is an illegal genetic experiment created by Jumba Jookiba. He is designed to drill potholes. His one true place is with Mrs. Hasagawa as one of her "cats". When not residing with her, he probably works as a construction worker. He is voiced by Jeff Bennett.
He was activated by a watering can. The episode "Mrs. Hasagawa's Cats" also features these experiments: 002 Doubledip: Designed to double-dip, 031 Gotchu: Designed to pinch, 044 Forehead: Designed to sing off-key, 051 Hocker: Designed to spit acid, 077 Zawp: Designed to be lazy, 111 Mulch: Designed to tear up the ground, 134 Shredder: Designed to shred paper, 214 Pix: Designed to take bad pictures, 288 Boomer: Designed to be a boomerang, 358 Manners: Designed to turn people polite, 507 Woody: Designed to eat wood, 521 Wrapper: Designed to wrap up things, and 533 Blowhard: Designed to blow things.
Derrick is a grey dinosaur-like experiment with black eyes, orange markings on his stomach, a tan stomach from his chin down and a drill-like tail, wearing a construction helmet.
Derrick can use his drill-like tail to drill potholes beneath him. Apart from drilling, he can create buildings and structures.
- Derrick's pod color is blue.
- Derrick is described by the experiment computer screen as, "Experiment 566. Primary function: Driller".
- Derrick is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.