Dennis Ryland
Dennis Ryland (Peter Coyote) was the original supervisor of NTAC, the federal agency created to investigate and oversee The 4400. Dennis was promoted to deputy director of NTAC and moved to Washington, D.C., leaving Nina Jarvis in charge. He soon returned, though, to oversee the investigation of the disease afflicting The 4400.

But it was later revealed that Ryland was, in fact, the mastermind behind The 4400's illnesses. His experiments aimed to control The 4400's abilities by inhibiting the production of promicin. He was arrested after his involvement was uncovered by Tom Baldwin and Diana Skouris.