Here's an ITC series that never saw the light of day in the home district that I know of.
Randall & Hopkirk (Deceased) aired in England in 1969, and when it was imported to America, it was given the alternate title, My Partner The Ghost, which is how I remember seeing the show in the listings in the New York papers back in the day. There, it aired on WNBC ahead of NBC programming on Mondays, as memory serves.
In the series opener, detective Martin Hopkirk (Kenneth Cope) is struck and killed by a hit & run driver. He returns as a ghost, enlisting the aid of his partner, Jeff Randall (Mike Pratt) to find said killer. However, Marty has remained on the mortal plane too long, and must remain for another several years, even if his murder is avenged.
Edit, 3/16/18: Unfortunately, full episodes of the original series are no longer on YouTube. We'll replace it with the intro, with music by ITC's top tunesmith, Edwin Astley:
After a short-lived revival in England in 2000, NBC-Universal acquired the rights in 2010, intent on developing a new version for SyFy. So far, nothing has come of it, and likely never will.