The Underminer (voiced by John Ratzenberger) is a short, almost mole-like creature who appears to be patterned after the Fantastic Four's first foe, the Mole Man. He first appears at the end of the first movie riding on a gigantic drill-tipped vehicle, where he announces his "war on peace and happiness!", leading into the last shot of the Parr family putting their masks on for battle.
This led to such a cliffhanger that the creators of the original Incredibles video game created the sequel, The Incredibles: Rise of the Underminer. As the Underminer unleashes various killing robots and machines on Metroville, the Incredibles fight off the surface invasion while Mr. Incredible and Frozone pursue the Underminer into the depths of his underground empire. It is revealed that the Underminer plans to activate a machine called the Magnomizer, which would heavily pollute the Earth above. The two supers destroy the machine, and the Underminer is supposedly killed in his final battle against the supers.
The Underminer first appears in the comic series as part of Dash's lengthy dream sequence. Having escaped the Sporlanx aliens with Violet, Dash finds that the Underminer is supposedly still alive, and has grudgingly allied with Violet to fend off the aliens. However, as the group escape underground, Violet is forced to lead the aliens to their location through a post-hypnotic suggestion. Enraged, the Underminer shoves Violet to the magma below (having decided to get some personal revenge out of the failed escape), but Dash's dream shifts perspectives afterwards. The Underminer later makes a full appearance as one of the Unforgivables, under orders from Xerek to soil the Incredibles' reputation by creating a giant robot painted in the super family's iconic colors and rampaging through Metroville. However, he is later eliminated after completing his purpose.
Several minions and/or creations of the Underminer are introduced in The Incredibles: Rise of the Underminer:
Read more about this topic: List Of The Incredibles Characters, Villains