Matthias W. Jefferies was a human Starfleet flag officer in the 23rd century.

In 2264, Admiral Jefferies served as Chief of Starfleet Operations and authorised the recommissioning of three Daedalus-class starships for use by the Starfleet Corps of Engineers.

He was interviewed about that decision by Federation News Service reporter Tim Pennington. (Star Trek Magazine #162: "Blast Off!")