More Than Meets the Eye
Transformers is a toy line created by Hasbro whose figures are vehicle-to-humanoid-robot transforming machines. The two sides are the Autobots, the good guys whose leader is Optimus Prime, and the Decepticons, the bad guys whose leader is Megatron, who've found their way from the planet Cybertron to Earth and whose struggle humans must now also face. Adapted into comics, television, movies and video games, the series has become an international phenomenon.
I should probably break this list up into sections. Date-of-release is a serviceable sorting method, but still.