Shockwave is one of the few Decepticons who doesn't seek power for himself. He serves logic. And that's exactly what makes him so frightening.
The classic Shockwave
In the 1984 cartoon Shockwave guards Cybertron for millions of years while the other Decepticons sleep on Earth. He is methodical, loyal to Megatron and never complains of loneliness. His signature trait is constantly talking about what is logical and what is not.
A scientist without limits
In modern versions Shockwave is a genius who experiments without any moral limits. In Prime he clones ancient beast-like Predacons. In Dark of the Moon he commands a giant worm that tears through Chicago's skyscrapers.
Why he's scarier than Megatron
Megatron can be understood: he's aggrieved, proud and power-hungry. Shockwave can't be understood in a human sense — he simply calculates. If the numbers say sacrificing millions is worthwhile, he won't hesitate. He's a cautionary villain about a mind that abandoned compassion.
