Wormmon is a small green silk worm-like creature and the partner to Ken Ichijouji. Like a real insect, Wormmon possesses the ability to adhere to surfaces and is also able to generate silk from its mouth.
Interestingly, he seems to have a Dark Ring round him, though clearly based on his behaviour in the series it is just part of his design. Seeing the ring on Wormmon may have inspired Ken to create the Dark Rings.
Wormmon is a main character in Digimon Adventure 02, and also appears in the movie Revenge of Diaboromon.
Wormmon's story begun when a young Ken Ichijouji was sucked into the Digital World for the first time via his brother's computer. Ken, along with Ryo Akiyama, travelled together with their Digimon through the Digital World desert, where they battled and defeated Millenniummon. With its death, Millenniummon released the Dark Spores, one of which burrowed inside Ken's neck.
The next time Wormmon met Ken, the boy had assumed the guise of the Digimon Emperor. Although Ken, as the Digimon Emperor, treated Wormmon cruelly; Wormmon still chose to stand by him out of friendship and loyalty. During this part of the series, Wormmon mostly served as a comic relief character. However, when Kimeramon was finally created and went on a swathe of destruction across the Digital World, Wormmon finally decided to make a final attempt to save Ken by defying him. Wormmon led Davis and Veemon to the Digi-Egg of Miracles, which turned Veemon into Magnamon. Ken still refusing to give up and with Magnamon losing, Wormmon took drastic measures and surrendered all its life force to Magnamon. This gave Magnamon enough power to kill Kimeramon, but it cost Wormmon his life. This last noble act, however, was enough to finally make Ken realize his evil doings and resign from them.
Wormmon was reborn as a Digi-Egg in Primary Village and reunited with his partner Ken. Ken then vowed to fix the damage he had caused and discovered that he was had been used by Arukenimon to establish the Control Spires that she was now turning into dark digimon. To fight the monsters created from the towers, Wormmon achieved the power to Digivolve to his champion form - Stingmon. The two became official members of the team when Stingmon merged with ExVeemon to form Paildramon. With Azulongmon's power, Paildramon was later able to Digivolve further into Imperialdramon.
Of all the protagonist Digimon of Digimon Adventure 02, Wormmon is the only one to have the Virus attribute; in fact, Wormmon was the first known Virus type partner Digimon in the Digimon anime series; the second being Guilmon of Digimon Tamers. He is also the only one to be able to digivolve to the champion level when a control spire is present, though this ability is sporadic as he occasionally is affected by the spires just as other Digimon are. Also unlike the other protagonist Digimon in the series (not counting the ones from the original DigiDestined), Wormmon was able to enter the human world without reverting to his In-Training form. In Dimensions, Book Three, Wormmon accompanies Ken to the tamer universe to fight the Demon Lords. Eventually, he and Ken gain the ability to Biomerge to form the mega level GrandisKuwagamon. They continue to be valuable additions to the tamers and they are closer to Ryo than any of the other tamers due to their shared history.