The Transformers toyline was developed by Hasbro after they met up with Takara representatives at the 1983 Toy Fair trade show in New York and proposed to combine and re-brand Takara's Diaclone and Micro Change toylines into the Transformers for release in the United States. Thus began a long and successful collaboration between Takara and Hasbro on toy development for the Transformers line, a collaboration which has grown increasingly close. Currently, Hasbro does the vast majority of the concept work and character creation, while Takara continues to control the actual manufacture of the toys. Hasbro markets and sells the toys internationally, while Takara sells them in the Japanese market. The design director for the Transformers brand, as of the first week of July of 2007, was Aaron Archer.
The basic back-story of the toyline and subsequent comic books and cartoons was developed by the Marvel Comics writers Jim Shooter and Dennis O'Neil; it was O'Neil who actually changed Convoy's name to Optimus Prime. Most of the subsequent character names and profiles throughout the original run were done by the primary Transformers US comic book writer, Bob Budiansky.
Floro Dery was primarily responsible for the look and feel of the Transformers cartoon series program, and he was the visual creator of The Transformers: The Movie. He refined some of the initial season one animated character models done in Japan, and subsequently interpreted the toy box art for further characters, creating the models that would become the visual guidelines both for the comic books and the animated cartoon.
Most Transformers come with "technical specifications" which detail the Transformer’s characteristics. Older Transformers come with Robot Points which could be redeemed for special Transformers which were not sold in stores, such as the Omnibots or the Decepticon triplets known as Reflector, a character who featured heavily in the early installments of the television series program, despite not being easily available as toys.
Source: http://en.wikipedia.org/wiki/Transformers_(toy_line)