Ultimately, I serve only one master... pure logic.
Shockwave is a Decepticon from the Transformers Franchise. He is usually treated as the "mad scientist" of the Decepticons. In some continuities, he is Megatron's true second in command but is forced to stay on Cybertron leaving Starscream as the acting second in command. Although he appears loyal to Megatron, his true loyalty lies in logic and would overthrow Megatron without hesitation if that is the logical choice.
Fear not, Megatron. Cybertron shall remain as you leave it.
~ Shockwave after having Megatron entrust the safety of Cybertron.
Shockwave was a minor Decepticon in the Generation One cartoon, but he did appear in some episodes as the main character. He was left behind by Megatron to look after Cybertron, with Shockwave announcing "Cybertron shall remain as you leave it". Megatron hardly showed any respect for Shockwave, such as in Desertion of the Dinobots where he threatened to make Shockwave become a maintenance worker if he fails to give the Decepticons enough Cybertonium to recharge and still be active for the war against the Autobots on Earth. Shockwave claims that he will only serve Megatron, learning of how Starscream wanted to make Megatron either surrender or die when the Decepticon Combaticons tried to move Earth into the sun. Shockwave's fate is unknown after the G1 movie. He was never seen afterwards. It is likely that Unicron killed him during his attack on Cybertron and Shockwave, small and weak compared to Unicron, did not survive the attack. His last known dialogue was, "Decepticons, we're under attack! Scramble!"
in The comics, Shockwave becomes the main villain for being an even more effective leader than Megatron in the Marvel comics.
in IDW comics he served as the main villain of Dark Cybertron.
War for Cybertron
Though Shockwave does not appear in the game's campaign, he does make an appearance in multiplayer. In a promo commercial for the character, Shockwave is placed as the commander of the Decepticons as Megatron retreats from the battlefield. Shockwave, now the leader of the tyrannical military, orders Soundwave to play the famous Touch song, known for being the iconic theme where Optimus Prime plows through armies of Decepticons and guns down Megatron. Starscream, annoyed, questions why they of all songs must blare that one, and Soundwave answers by saying when he's the commander, he can pick battle soundtrack.
Fall of Cybertron
Shockwave is first seen operating machinery in the middle of an Energon reservoir. Starscream berates him for wasting both time and resources, but Shockwave shrugs it off, saying that the Air Commander simply doesn't understand.
Far later, he, along with several Insecticon minions, are shown to be experimenting on the Dinobots in an attempt to have them transform. After gathering enough results, he leaves the complex just before Grimlock escapes and goes on a rampage through all the chambers and frees his teammates, but Shockwave still mocks him via audio and holograms throughout the mission. Near the end of the game, he is encountered again, preparing the final adjustments to his tower and Space Bridge. He briefly succeeds in restraining Grimlock, saying that he would not have made something so powerful without adding a way to control it. However, Grimlock transforms to his alt mode, bites off Shockwave's left arm, and tosses him aside.