|Name|| Egregious Heterodyne|
|Occupation|| Dynamic Hydrologist|
|Residence|| Castle Heterodyne, Mechanicsburg|
|First Appearance|| |
|Relatives|| House Heterodyne|
|Children||Presumably the ancestor of later Heterodynes.|
Egregious Heterodyne is one of the Old Heterodynes, and thus one of Agatha's ruthless ancestors. He destroyed the first Castle Heterodyne, built on the site of the spring that was the family's power source. Having concluded the spring was too small he decided, like a true spark, to increase its flow in the most egregiously destructive manner , with massive consequences for everybody around. The result was the destruction of the original castle and the creation of the River Dyne. He considered this a success.