Commander Mark Reasons was a crewmember of Enterprise-D in 2364, he was assigned in Stores and Supplies. He was talking to Jean-Luc Picard when the latter met Wesley Crusher, Data and William Riker coming out of the Holodeck Jean- luc promised to meet him after (TNG novelization: Encounter at Farpoint) Reasons was referred to as "commander", it is possible he was either a lieutenant commander or a full commander.