Bio

From the very beginning, the Transformers toyline distinguished itself by providing on-package bios for its characters. Rather than needing to watch the show or read the comic, a customer could read the write-up on the box and know who the toy was supposed to be. In fact, this practice eventually gave "life" to hundreds of characters who would never play a part in any story. It also spread beyond the packages to comics, trading cards, and magazines, continuing to this day.

Generation 1
Although bios had a tendency to describe some characters as having complex personalities, the cartoon often underutilized them.

Beast Wars
In Beast Wars, bios became noticeably less character-driven. Rather than describing personality, history, or character quirks, they frequently amounted to a bit of purple prose describing the animal mode in the wilderness and maybe a brief weapon or power call-out.

Also notable is the disconnect between the first wave of bios and their eventual cartoon portrayals. In both their bios and their pack-in comic, Optimus Primal and Megatron were implied to be their G1 namesakes in new bodies on modern, human-inhabited, post-Generation 2 Earth. When the BW cartoon began, the bios abandoned this micro-continuity in favor of the cartoon's continuity. But even aside from blatant continuity issues, there were still more subtle disparaties. Tarantulas was portrayed in his bio as a ninja, while Rhinox was portrayed as a security officer, yet both characters were later revealed to be scientists of incredible skill (although Tarantulas did like preying on animals, and his tech spec indicates he preys on humans, so the cartoon at least used some of it).