NBC Films

Background
NBC Films (also known as "NBC Enterprises, Inc.", which would later reform in the late 1970s) was the production/distribution arm of the NBC Television Network for NBC off-network programs originally formed in 1952. In 1973, NBC later spun-off NBC Films and later sold it including the library to National Telefilm Associates because it was against the FCC regulations for a television network to distribute its programs under its own name. As of now, most of the library is currently handled by Paramount Global, through CBS Media Ventures and Spelling Television Inc., except several episodes of You Bet Your Life by Buddy Hackett and non-public domain episodes by Groucho Marx are retained by NBCUniversal. Many others have fallen in the public domain.

1st Logo (December 18, 1953-1955)
Visuals: On a background, a series of three filmstrips draw themselves in, spelling the letters "NBC". After all three filmstrips are on-screen, a straight filmstrip with the words "FILM PROGRAM" appears below them.

Variant: A still variant exists.

Technique: 2D animation.

Audio: None.

Availability: This logo can be spotted on Starz Encore Westerns' prints of The Adventures of Hopalong Cassidy episodes "Frontier Law", "Don't Believe in Ghosts" and "Outlaw's Reward", and every episode of season 2 on Amazon Prime Video.

2nd Logo (January 9, 1954-1961)
Visuals: On a background filled with filmstrips with the letters "NBC" inside, the text "AN NBC FILM PROGRAM" in 3D zooms in while the NBC filmstrips light up from one section to another. The word "AN" is small and on top, "NBC" appears in giant 3D letters and "FILM PROGRAM" appears to be chiseled on a 3D bar.

Technique: Simple lighting and zooming effects.

Audio: The end title theme from the respective show.

Availability: One of the series that had this logo was Inner Sanctum and His Honor, Homer Bell.

3rd Logo (September 22, 1960-1966)
Visuals: There is a spinning filmreel with the NBC snake forming in the middle just like in the NBC cameraman logo. Inside the letter "C" we see the word "FILMS" and the copyright stamp is below the logo.

Technique: 2D animation.

Audio: The end title theme from the respective show.

Availability: Seen on You Bet Your Life with Groucho Marx on DVD.

4th Logo (September 1963-1966)
Visuals: An in-credit logo that features "IN ASSOCIATION WITH", and the NBC snake logo below with the word "ENTERPRISES" next to it.

Variant: On Kimba the White Lion, the in-credit text reads "An NBC Enterprises Presentation".

Technique: None.

Audio: The end title theme from the respective show.

Availability: It's seen on Astro Boy and Kimba the White Lion, among other programs. The former appears from time to time on Adult Swim's Toonami block.