By any measure--original ratings, syndication runs, merchandising, fan appeal--the most popular of all the Gerry Anderson series remains 1965's THUNDERBIRDS, the 32-episode series that became the defining series for a generation of Brits just as STAR TREK was for a generation of Americans. According to SCIENCE FICTION AND FANTASY MODELER correspondent Marc Frattasio, the popularity of THUNDERBIRDS in the UK can perhaps be best illustrated by at least one report in the London newspapers around 1990 that a sexual bribe was offered in return for the privilege of purchasing examples of the Matchbox THUNDERBIRDS toys which were then in very limited availability in stores.
A close second is 1967's CAPTAIN SCARLET AND THE MYSTERONS; though it never developed the audience THUNDERBIRDS did, SCARLET has done extremely well in worldwide syndication, in merchandising, and in its recent BBC revival, and has a strong core group of devotees. SCARLET appears particularly strong in the fan fiction realm; when the official Gerry Anderson Appreciation Society, Fanderson, recently resumed publishing its sanctioned fanzines, the production staff had to specifically request no more CAPTAIN SCARLET fan fiction submissions as they were overwhelmed with the volume of SCARLET stories they had already received.
The live-action shows UFO and SPACE:1999 also have strong fan bases and are enjoying new lives thanks largely to renewed syndication in recent years for both shows and internet mailing lists devoted specifically to them; thanks largely to those lists, 1999 and UFO finished first and second in the "Favorite Show" category in a recent survey of Anderphiles by POWER STAR Magazine. The earlier puppet shows THUNDERBIRDS and SCARLET finished third and fourth, respectively. Interestingly, SCARLET and UFO tied for the top spot in the "Other Well-Liked Shows" category, and 1999 finished second to "No Preference" in the "Least-Liked Show" category.
There appears to be a strong dividing line between the live-action productions and the puppet productions; fans of the former tend not to be as enthusiastic about the latter, and vice versa. Still, with the variety of work Anderson has produced over the years, there is something to appeal to almost everyone.