Origin

Lee Kelso was born in San Fransisco, California.  Kelso went to Starfleet Academy and was part of James Kirk's class.  He would later serve under Kirk as a Helmsmen when Kirk was Captain of the U.S.S. Enterprise.
 
During his last mission Kelso and the rest of the crew went to the Great Barrier.  It was after this incident that his close friend and fellow crewman Gary Mitchell developed Super-human powers.  These powers became so great they warped his mind.  Kirk decided he had no choice but to abandon him the deserted planet Delta Vega. It was here that Kelso was to oversee Mitchell's interment. But Mitchell killed him with his powers and escaped.  

Creation

Lee Kelso was created for the original Star Trek series.