Lt. Leslie
Lt. Who What Now?Lt. Who What Now?
Lt. Leslie has served as *deep breath*... Duty Officer, Engineer, Helm Officer, Medical Assistant, Navigator, Science Officer and Security OfficerDuty Officer, Engineer, Helm Officer, Medical Assistant, Navigator, Science Officer and Security Officer. He appeared in 57 TOS episodes57 TOS episodes and has the remarkable ability to return from the dead several timesreturn from the dead several times (or Dr. McCoy was drunk when he pronounced him dead) and quickly change uniforms and duties within a few minutes.
Blue / Sciences (TOS: Where No Man Has Gone BeforeTOS: Where No Man Has Gone Before)
Red / Operations (TOS: The Squire Of GothosTOS: The Squire Of Gothos)
Gold / Command (TOS: The ChangelingTOS: The Changeling)
Out of universe, Lt. Leslie is obviously the result of TOS reusing the same stable of actorsTOS reusing the same stable of actors and not paying close attention to continuity. In universe, Lt. Leslie appears to have some very remarkable qualitiessome very remarkable qualities leading to some theories that he's actually several people or a remarkable alien or a quick change artist or an incredible savant.
And yes, he does have lines and is named on screenhe does have lines and is named on screen.