Man From Atlantis
The science fiction TV movie-of-the-week Man From Atlantis airs on NBC, starring Patrick Duffy and Belinda J. Montgomery. Created by Mayo Simon and classic Star Trek veteran Herbert F. Solow, Man From Atlantis centers around a mysterious man from the ocean (Duffy) discovered by humans, who find he is willing to live among them and coexist for peaceful purposes. Three more TV movies will follow, each successful enough for NBC to greenlight a weekly series in the 1977-78 season. 
Hear about it on the Sci-Fi 5 podcast