The Indigestible Man is an agent and associate of the notorious crime boss Chairface Chippendale. He specialises in the rather unorthodox field of human body diving. He uses advanced technology to shrink himself down and inject his indigestible body into the target of his choice. A computer and a pair of electrodes allow him to gain access to the brain's functions, effectively allowing him (or whoever is employing) him to control the body of the person that the Indigestible Man currently inhabits.
He was brought in during Dot and Neil's wedding to take over the mind of an agitated and monstrously-larged Dinosaur Neil. He succeeds in turning over power to Chippendale but is eventually defeated by the Tick and expelled from the body like so much fatty substance.