Soundwave

Soundwave is the communications and surveillance expert of the Decepticons, he can hack into the toughest computers and equipment. He is one of Megatron's right hand 'bots, along with his menagerie of Ravage and Laserbeak. Soundwave is almost as cold and calculating as Shockwave, and very intelligent. Starscream hates him for one reason: If any Decepticon is disloyal or disobeys Megatron, he sends the footage to Megatron, and watches him tear the unfortunate apart. Starscream is always on his best behavior around Soundwave.

In satellite mode, orbiting planets, he keeps watch over the Decepticons. On Cybertron, he guided drone attacks from above the surface. He has always kept away from direct combat.

In Revenge of the Fallen
Soundwave sent Wheelie to spy on Sam Witwicky at his home, and then ordered him to retrieve the Allspark shard being held by Mikaela Banes. Soundwave later hacked into a satellite by merging with it via tentacles. He acquired all the frequencies and signals from the satellite, and thus listened in on a NEST debriefing. From it he discovered the location of the last AllSpark fragment and Megatron's corpse from Theodore Galloway's rant. He then deployed Ravage to Diego Garcia to retrieve that AllSpark shard and to rendezevous with the Constructicons to revive Megatron.

Once Megatron was revived and had ordered the Decepticons to openly attack Earth, Soundwave ordered: "Decepticons Mobilize...It is time." He kept track of the AllSpark-empowered Sam's parental units. He called Judy Witwicky on her cellphone, demanding to know where he was hiding. She did not understand Soundwave's deep voice, calling him a perverted mouth-breather and hung up. From this he decided to send some Decepticon Protoforms to retrieve Sam's parents from their location in France. Later, he located Sam in Egypt via a security camera which transmitted the face to the satellite and Starscream was sent in pursuit.

In Dark of the Moon
During the 1970s, Soundwave had tried to hide the Ark's presence on the moon by gaining human contacts in the United States and Soviet Union, whose creative accounting would render further trips to the moon financially unfeasible. One of these was Dylan Gould's father, while Dylan himself would later accept Soundwave as a "client".

Three years after "Operation: Firestorm" and the death of the Fallen, Soundwave had separated from the satellite and adopted the form of Mercedes-Benz SLS AMG. The communication's officer hid out in the plains of Africa with Megatron and the other Decepticon's were they lived in exile. Soundwave, Starscream, Laserbeak and the diminutive Igor were the only ones under his command.

Soundwave met with Megatron and Starscream at an outpost in Nambia, Africa. He and Laserbeak reported on the Autobots finding of The Ark and Sentinel Prime on the Earth's moon. Megatron noted that Soundwave had done him great honor tracking the Ark, and having decided that they had served their purpose, ordered Soundwave and Laserbeak to eliminate their human collaborators. One of these was Jerry Wang.

Later, disguised as a Mercedes he was given as a gift to Carly Spencer from Dylan Gould, the only human operative Soundwave spared from termination, in order to spy on both her and Sam Witwicky. When Sam and Carly realized Dylan was a Decepticon agent, they attempted to escape in Soundwave, only for him to reveal himself and trap Carly in his vehicle mode. Dylan revealed that Soundwave and Laserbeak had been to Earth before, in order to cover up as much of the Ark as possible and to steal Sentinel's Space bridge pillars. Soundwave threatened Carly with his tentacles in order to force Sam Witwicky to cooperate and discover the Autobot's plans. He soon escorted some of the pillars to Chicago for Megatron and Sentinel.

During the battle in Chicago, Soundwave, Barricade and several Protoforms captured Sideswipe, Bumblebee, Dino, Que, and Ratchet. However, Dylan appealed to Soundwave's violent side, persuading the Decepticon to give the order to execute their Autobot prisoners. Barricade killed Que, then Soundwave took Bumblebee and began leading him to his death. Soundwave prepared his sonic cannon to shoot Bumblebee when, at the very last second, Wheelie and Brains crashed the Decepticon mothership nearby, raining stored fighters onto the Autobots and Decepticons.

Bumblebee took advantage of the distraction and attacked Soundwave with a punch and a kick to the face, engaging in a firefight with Soundwave. Soundwave was not able to get a good shot on Bumblebee, even accidentally hitting his comrades while targeting the light footed Autobot. After receiving several blows from Bumblebee, Soundwave caught hold of Bumblebee's back, throwing him. Bumblebee then shot Soundwave on the leg. He lurched onto Bumblebee, who knocked his sonic cannon out of his hand, giving him a punch to the gut before Bumblebee rammed his canon into Soundwave's chest before firing upwards, blasting his head off his shoulders. The blast killed him immediately as Bumblebee threw his lifeless body onto the road.

Trivia

 * Soundwave will appear in Thomas and Twilight Sparkle's Adventures of Transformers Revenge of the Fallen, and our heroes will encounter him in Thomas and Twilight Sparkle's Adventures of Transformers Dark of the Moon.