Soundwave

Soundwave, the Decepticon communications officer and one of Megatron's staunchest supporters, doesn't just master the frequencies that carry information across our planet, he revels in them. Stationed high in the upper atmosphere and capable of processing millions of data streams at once, he is fully capable of taking over communications on a planetary scale. Whether he uses this to direct civilization or destroy it remains to be seen.
Soundwave has two extremely powerful weapons: his spread of Sonic Cannons... and Megatron. If any Decepticon crosses him, he does not hesitate to send a full record of said Decepticon's failures to Megatron, almost certainly ensuring an untimely demise. His lofty position has made Starscream suspicious, so Soundwave has his minion Ravage keep an eye on the Air Commander if he gets out of hand. Soundwave is also nearly defenseless in space, as his devastating Sonic Cannons only work within the atmosphere.