The Thin Man was not Nick and...

...The Night Stalker was not Kolchak. The Night Stalker was the vampire in the first stand alone made for TV movie. A fact corroborated by the sequel stand alone film that followed called "The Night Strangler". The TV show made Kolchak synonymous with the moniker Night Stalker but he in fact was not.

Oh and The Thin Man? He was a character of interest in the first William Powell\Myra Loy detective mystery about Nick and Nora Charles. The film was called "The Thin Man" and in the sequels Nick was forever associated with the thin man. Yes, Powell was thin but never once in the sequels was he called The Thin Man even if the movie's titles ("The Thin Man Returns", "Another Thin Man", etc) perpetuated the identity myth.