John M. Dwyer was a Starfleet officer in the 24th century. He was a captain in 2363.
In 2368, he was listed as a Engineering Group officer on the second version of the dedication plaque of the USS Enterprise-D. (TNG: "Silicon Avatar", dedication plaque.)
In 2372, he was listed as a Systems Management officer on the dedication plaque of the USS Enterprise-E. (Star Trek: First Contact, dedication plaque)
This character was only mentioned in writing.