Jeff Regan, Investigator was a private detective radio drama series that aired on CBS from July 10, 1948, to December 18, 1948, and again from October 5, 1949, to August 27, 1950. The series initially starred Jack Webb, known for his later work in Dragnet, as the hard-boiled investigator working for Anthony J. Lyon at the International Detective Bureau. The show featured talented voice actors such as Herb Butterfield, Wilms Herbert, and Frank Nelson, and was written by notable talents like E. Jack Neuman, Larry Roman, and William Froug.

Following Webb's departure in 1949, actors Frank Graham and Paul Dubov took over the role of Jeff Regan. The series came to an unexpected end after the sudden death of Frank Graham in 1950. Although never airing beyond CBS' West Coast network, Jeff Regan, Investigator remains a strong example of mid-century detective dramas, thanks to its impressive cast and talented writers.