From 1996: one of the best freebies in the long-running history of SFX MAGAZINE: Volume 1 (or 2) of THE EPISODE GUIDE TO THE GALAXY.
This was a no-pics paperback which, as the name suggests, gave concise-but-informative episode guides to BABYLON FIVE, STAR TREK: VOYAGER and SPACE: 1999. The former two shows were still in production whilst, of course, the last had wrapped almost twenty years earlier.
These weren't the old fashioned summaries of the plots that older guides focused on, these borrowed far more from the much-missed Virgin Books house style of throwing in behind-the-scenes information, analysis, context and the odd scathing observation.
A second volume followed the next year and then, sadly, the project ground a to a halt. I imagine the economics of such an undertaking, especially in the age of the web, didn't justify the potential sales spike.