TV spin-offs — the idea of a successful show spawning one or more series featuring either a regular or recurring character — are certainly nothing new in the history of Classic TV. Neither is the idea that those, in turn, could spin off yet other series enjoying equal success. A great example is The Danny Thomas Show from the 1950s, which featured Andy Griffith and the town of Mayberry as a guest star, which eventually became The Andy Griffith Show. And that show birthed the Jim Nabors series Gomer Pyle USMC, and, when Griffith decided to end his show, it became Mayberry RFD, starring Ken Berry.

There are other successful spin-off stories out there — some more so than others — like Law & Order (four shows), CSI (four shows), Happy Days (seven shows), The Brady Bunch (four shows), and The Mary Tyler Moore Show (three shows). But there are a lot more that didn't quite make it, despite the fact they actually went into production. The difference is that their time on the air could have spanned anywhere from one or two seasons, to a handful of episodes. What follows is our look at 18 of those shows. Check 'em out and see how many you actually remember.