Wormmon

He is the digimon partner of Ichijouji Ken. At first he is a loyal but abused servant of Ken, but in the end he becomes a good friend and partner to the kids and their digimon.

[Spoiler] During the series he sacrifices himself in order to help defeat Chimeramon, but reborn as a digi-egg. From thereon he is the friend of Ken. His evolved form is called Stingmon and in this form he can fuse with ExVeemon and become Paildramon. [/Spoiler]