Lieutenant commander Dimitri Valtane was a male Human Starfleet science officer in the 23rd century. From 2290 to 2293, Valtane served on the USS Excelsior under Captain Hikaru Sulu for its three-year mission cataloging gaseous planetary bodies in the Beta Quadrant. His living quarters was on deck 7, along with bunk-mate Ensign Tuvok and two others, who all worked during the gamma shift. (Star Trek VI: The Undiscovered Country; VOY: "Flashback")