People sometimes talk about the year Fun Publications took over BotCon (2005) as the year when the number of BotCon exclusives began to jump to huge proportions. While it is certainly true that Fun Publications' business model does involve putting out a large number of exclusive toys every convention, and that many of them must be purchased bundled together rather than separately, the trend toward more exclusive toys per convention had actually started a few years before Fun Publications entered the picture.
BotCon 2002 was the first convention for which then-showrunners 3H had secured the official Transformers convention license from Hasbro. In some ways, this is an academic point, because BotCon had gotten support from Hasbro since the very beginning, as demonstrated by the exclusive toys created from Hasbro's molds every year since the convention started in 1994. However, BotCon 2002 saw a jump from the then-standard two exclusive toys at the convention (itself up from just one prior to 1997) to four exclusive toys. Two of these, Tap-Out (featured on the old blog several years ago) and Glyph, were new characters created from molds that dated back to the beginning of the franchise in 1984, an unprecedented situation for BotCon.* Indeed, no complete molds from the Generation One-era—let alone from 1984—have ever been used for BotCon toys since then (with the exception of Rook, which itself was also released for a 2002 BotCon, but that one was for BotCon Europe).**
Long-time Transformers fans will immediately recognize Glyph as using the original Bumblebee mold, with the caveat that it (like Tap-Out and Rook) has the keychain ring added to it by Fun4All, who had revived these molds to be used as keychains. Indeed, even the BotCon versions included a metal keychain attachment, which I've long-since disposed of. Glyph is also distinctive in being an early example of a female character with an actual toy in the Transformers franchise, although it is certainly recognized that (outside of the then-current Beast Era) nearly all such examples had been, themselves, BotCon exclusives.
Unlike most older BotCon toys, the odds are pretty good that you can find Glyph for a reasonable price if you're interested in looking for it. 3H reportedly had to order 3000 units of each of these "keychain exclusives," a number still unmatched even in the modern era of BotCon exclusive toys. Happy hunting!
*Of course, BotCon 1994 did offer G2 Breakdown, whose mold was created for the original Breakdown which came out in 1986. However, besides not being a new character, G2 Breakdown was originally intended by Hasbro for the retail market, rather than for BotCon. It was only after Hasbro decided not to produce the G2 Stunticons further that Breakdown was offered as an exclusive toy.
**One could also make a case for Action Master G2 Breakdown, which was offered as an exclusive to folks who attended the convention breakfast (not merely the convention itself!) at BotCon 2004, but this wasn't an official convention, and Action Master G2 Breakdown didn't use the actual Hasbro mold for Action Master Sideswipe. Rather, a fan-made mold was created from Action Master Sideswipe for this exclusive, which makes it rather a different kind of thing. Honorable mention also goes to BotCon 2014 Scorponok, which mostly uses the Energon Scorponok mold, but the Headmaster head does use the Generation One Fortress Maximus "Spike" mold as its basis.