Grundel Toad (voiced by the late Joe Lynch) is the main antagonist of Jaden Meets Thumbelina. He was madly in love with Thumbelina, but he was using all the wrong methods to win her. He blackmailed Berkeley Beetles into helping him by taking his wings, tried to get rid of Prince Cornelius the fairy prince, and his mom kidnapped Thumbelina. After crashing a wedding Mr. Mole had set up for him and Thumbelina, he chased after Thumbelina, until Cornelius showed up and challenged him to a fight, until they both fell into a chasm. By the end, Grundel survived and married a female toad, but he wants revenge on Jaden for angering him.
- Grundel will be one of many villains in Jaden's Adventures of Fantasmic!
- Grundel will become Jeffrey's enemy in Jeffrey & Friends meet Thumbelina.
- Grundel will guest star in Jaden gets Hoodwinked!
- Grundel will guest star in Pooh's And Jaden's Adventures of ChalkZone The Big Blow Up.
- Grundel will return for revenge in the Jeffrey, Jaden & Friends meet Indiana Jones saga.
- Grundel will guest star again in Jeffrey, Jaden & Friends' Storm Adventures of Epic. In it, he takes Beetles wings again.