Cannon

Cannon was the first Quinn Martin production to air on a network other than ABC, debuting on CBS instead.

The series began as a two-hour pilot movie on March 26, 1971, in which Frank Cannon investigates the murder of a close friend after returning from an overseas assignment; the character's backstory involving his wife and son's death by a car bomb was only revealed in a later episode.

William Conrad was the only main cast member for the entire run; the series had almost no recurring characters besides guest stars like Martin Sheen, who played two entirely different characters in the first and third seasons.

Cannon was the only stand-alone 1971 debut network prime-time show to be renewed for a second season, since the other debut renewal, Columbo, was part of the NBC Sunday Mystery Movie rotation rather than a stand-alone series.

After three consecutive seasons in the Nielsen Top 20, the show's ratings dropped to 39th in season 5 amid increased plot violence and controversial themes, leading to its cancellation.

Throughout the series, Frank Cannon drove a succession of Lincoln Continentals, starting with a 1970 sedan in the pilot and switching to two-door Mark III and Mark IV models each season, while the 1980 revival film had him driving a 1978 Cadillac Coupe de Ville instead.

Cannon's car featured a rare Motorola MTS mobile phone prop, an early precursor to modern cell phones, which was unusual for the era and required Cannon to ask an operator to dial calls for him.

The premiere episode of the spin-off series Barnaby Jones, 'Requiem for a Son,' was originally written as a second-season Cannon episode before being reworked once Barnaby Jones was sold as its own series, with William Conrad appearing as a special guest star.

British comedian Benny Hill parodied Frank Cannon alongside other 1970s TV detectives like Ironside, Kojak, and McCloud (plus Hercule Poirot) in a skit on his Thames Television show.