The Alligator Imagin appeared in 2009 TV series called Kamen Rider Decade. The Alligator Imagin (アリゲーターイマジン Arigētā Imajin), based on the story of The Fox and the Crocodile (キツネとワニKitsune to Wani), is an Imagin who enacts his own scheme to change the past and is able to emit energy waves from his arms.
Unlike other Imagin, the Alligator Imagin goes through a multitude of hosts to enact his scheme. Arriving in the past on December 30, 2008 via a child, the Alligator Imagin proceeds to change the future and overpowers Decade and Den-O, taking the latter's DenGasher as his own.
Diend and his Kamen Ride Card summoned Riotroopers allow for Den-O and Decade to regroup, and allow for Decade to get the Den-O Cards. With both Kuuga and Den-O, Decade destroys the Alligator Imagin with the Den-O Final Attack Ride.
In the World of the Rider War, a copy of the Alligator Imagin was created by Super Apollo Geist by combining the Imagin. This Alligator Imagin is destroyed by Decade Complete Form's Enhanced Dimension Kick.
He was revived in Super Hero Taisen as a member of Dai-Shocker. Dai-Shocker eventually revealed their alliance with Dai-Zangyack and battled the army of Kamen Riders and Super Sentai. He is seen fighting Kamen Rider Agito and GekiBlue.