Transformers are cybernetic shapeshifting alien robots in disguise. Hailing from the war-torn planet Cybotron, they are an ancient race fueled with righteous might and terrible secrets, what some might call 'more than meets the eye.'
They claim to want to defend their homeworld and also protect the planet Earth but their battles against their enemies usually level entire cities with thousands if not millions of human casualties. This is because we are crushed beneath their feet like so many ants. Still, they turn into sweet vehicles with slick sound systems that play sick summer jams.
So it's a wash.
Decepticons are the badass villains of Cybertronia, dedicated to stealing energon cubes and the Allspark to reign supreme across the cosmos. Their leader is Negatron, who can turn into three things, one of which is a fucking gun. They use their cunning guile and their mighty powers to outmaneuver the stupid Autobots, always escape if they are somehow defeated, and have flourishing rap careers and this is why the Decepticonz are the Most Powerful Characters in the Revengerists Omniverse. Except Starscream. He can suck a robotic dick.
The first, ancient Transformers to land on Earth millions of years ago, they became unstable because there were no vehicles to emulate, and instead started transforming into the local fauna. This is against cyber-law, but their isolation at being crash-landed, and the constant grating voice of Rattrap, drove the Dinobots to utter insanity. Now they are little more than mindless beasts. Awesome ones.
Seriously? Wtf, Go-Bots. God, you suck. More like... GTFO-Bots. Heh. I just thought of that.
Mysterious ancient robot warriors from space may have also been responsible for the technological rise of the MesoAmerican civilization, though it is unknown if these were Transformers, or if Techuan Prime and others were just of a similar robotic alien race.