I’m adding a few I can’t believe I overlooked:
Dragnet with Jack Webb. Without it there’s no “police procedural,” ever. It was the first show to accurately depict police work as largely routine with few shootouts and car chases. It was also the first TV show with a dedicated Christmas special. When he died, Jack Webb was given a funeral with full LAPD honors and Joe Friday’s badge number was permanently retired by the LAPD.
And speaking of shows set in LA…
The White Shadow with Kenny Howard. Dealt with subjects like teen pregnancy (no abortion themes!), racism, homosexuality, drug use and all sorts of serious themes when no shows in the 70s would touch them - and had fun basketball scenes too.