Brettner in Riker's service record
Admiral Brettner was a Starfleet flag officer in a fictional future created for William T. Riker.
In 2367, while exploring a cavern on Alpha Onias III, Commander Riker was rendered unconscious by gases. While unconscious, neural scanners scanned Riker's brain. The scanners used elements of Riker's reality and constructed a holodeck simulation with those elements interspersed throughout, so that it felt real to him. What Riker wanted, the scanners made possible.
In one of these simulations, Starfleet Admiral Brettner awarded a commendation for exceptional leadership to Captain Riker, of the USS Enterprise-D, on stardate 57398, during the joint Excalbian Campaign. In 2383, this admiral was mentioned in Riker's service record that was on display in his quarters on the Enterprise-D. (TNG-R: "Future Imperfect", okudagram)