(written from a Production point of view)
He began his career playing one of Rick Nelson's fraternity brothers, Sean, on The Adventures of Ozzie and Harriet. Sean was a college buddy of casting director Joseph D'Agosta, who got him his roles on Star Trek. He made one guest appearance as Sean in 1964 (with Bill Mumy), becoming a regular cast member in 1965 until the end of the series in 1966.
His other television credits include Voyage to the Bottom of the Sea (1966, with "The Neutral Zone" guest Peter Mark Richman and Arch Whiting), CHiPs (1977, with Star Trek: Voyager guest Robert Pine), The Lucy Show (1968, with TOS recurring guest Barbara Babcock and VOY/ENT guest Robert Pine), Wiseguy (1987, with DS9 guest Jonathan Banks), and Unsub (with TNG/DS9 actress Jennifer Hetrick).
He appeared on Mannix three times: in 1968 (with VOY guest Joseph Campanella and "Patterns of Force" guest David Brian), and twice in 1970, with Robert Ito and Star Trek V: The Final Frontier actor Bill Quinn. He also appeared in the 1980 TV movie Reunion with Star Trek: Enterprise actress Joanna Cassidy.
His film credits include Vision Quest (1985, with TNG guests Jana Marie Hupp and Ronny Cox and Star Trek: Voyager guest Raphael Sbarge), What's Up, Doc? (1972, with Stefan Gierasch, Graham Jarvis and Kenneth Mars), and Harry and the Hendersons (1987, with William Frankfather, David Richards, John Bloom and Kevin Peter Hall).
Morgan eventually left acting to pursue a career in financial services and insurance. Today, he lives in Kalispell, Montana. 
Morgan was also erroneously credited in the first edition of the Star Trek Concordance in "The Paradise Syndrome". The part was actually played by John Lindesmith. Morgan was also credited for roles in "The Corbomite Maneuver" and "This Side of Paradise" that seem to have been cut.