Henry Deacon (Joe Morton)Henry Deacon is technically the town mechanic in Eureka, a community in the Pacific Northwest planned by President Harry S. Truman as a place for Americas most brilliant minds to work on breakthroughs in science.But like many in the community Deacon is not exactly what or who he appears to be.Working in an auto shop is not what takes up most of Deacon's time, however, since he is actually a physicist and an engineer and thus useful to Eureka in other ways.He is literally a jack of all trades, and he becomes indispensable to Sheriff Jack Carter. He is often involved in solving the problems that arise when the various experiments by the residents geniuses of Eureka go awry.Playing up his jack of all trades image, Deacon officially changes his title with each job with a Velcro patch on his overalls. He is qualified to work as everything from coroner to teacher to ballistics expert for the police. He has interacted in some capacity with almost all of the residents of Eureka.Deacon is at once very capable but also some of his technical gizmos fail in spectacular ways.Prior to coming to Eureka Deacon worked as a rocket scientist at NASA.