Soundwave

"Increase efficiency or be terminated."

- Soundwave to his human slaves

Soundwave is a Decepticon in the Transformers franchise. He was Megatron's most loyal minion and transforms into a cassette player. Unlike the most other Decepticons, he is emotionless, but probably due to his more "robotic" character traits.

In the original cartoon, the Michael Bay films, and Prime, Soundwave is portrayed by famous voice actor Frank Welker. In the Cybertron games, he is played by Issac C. Singleton Jr, and is portrayed by Jeff Bennett in the Animated series.

Generation One
"As you command, Megatron."

- Soundwave, loyal to the end

Soundwave is the most loyal Decepticon to Megatron, fitting comfortably in the highest Decepticon ranks. Like Starscream and Shockwave, he is one of the most important and powerful Decepticons, but only he completely obeys Megatron's commands while Shockwave is individual (or at times alert Megatron if a situation occurs) and Starscream tries to secretly replace Megatron. He has several minions similar to G1 Autobot Blaster, and his Decepticon followers are Ravage, Laserbeak, Ratbat, and Rumble. In the film, he had a very minor role where he was fighting the Autobots at the beginning, but then he must ally himself to his bitter enemies to destroy Unicron at the end of the movie. He then again was a loyal Decepticon to Megatron, who was now rebuilt into an even more powerful megalomaniac named Galvatron.

Live-Action Movies
Main article: Soundwave (Transformers Film Series) 

Soundwave is a major antagonist in the live-action movie series, debuting in Revenge of the Fallen.

Animated
Soundwave is also in Transformers: Animated. Soundwave was created by Megatron, who tells his creation that humanity is now depending on robots as modern conveniences in their lives. In a similar way of the Matrix series episode, "The Second Renaissance", he controls all the robots in Detroit, Michigan to eliminate the Autobots and the humans, but Soundwave was defeated by Autobot Bulkhead and the controlled robots were back to normal. He returns again in the third season and steals the Autobots' bodies to replace them with human bodies so that he can control the Autobots and turn them into Decepticons. However, when Autobot Prowl broke free of the control, he freed the other Autobots and Optimus Prime destroyed him with his own minion Laserbeak.

Transformers: Cybertron (Unicron trilogy)
Main Article: Soundwave (Transformers: Cybertron)

War for Cybertron
In the beginning of the game, which are the days the Cybertronian war is in its infancy, Soundwave starts off as Megatron's personal assistant on the battlefield, along with Breakdown. After the Decepticons launch a full scale assault on the Autobots' headquarter city, Iacon, the trio land and fight their way through to find Zeta Prime's, the Autobot's leader, secret vault, which contains the key to the core Cybertron. After hours of Autobot slicing and slaughtering, they finally arrive to the vault by blowing the entrance open via a Dark Energon airstrike. They enter the vault and find the key, only for Zeta to appear and battle the three with his overwhelming power. Soundwave himself is even aghast and impressed by Prime's advanced technology (which triggers Breakdown to call the studious soldier a "nerd") and gives his allies specific instructions on how to destroy their enemy. After gunning Zeta down, they take a wounded Prime and the key only to find out that the key doesn't actually unlock Cybertron's core, but its several hundred foot tall guardian, Omega Supreme, does.

So the trio and a fleet of Decepticon fighter jets make their way to the core only to be ambushed by Omega, starting a large violent war between the single robot and the army of Decepticons. Finally Megatron, Soundwave, and Breakdown defeat the beast and forces him to unlock the core. He complies and Megatron evilly infects the core, thus the entire planet, with gardens of Dark Energon, confirming a victory for the 'cons. Later, Soundwave is crowned the warden of Kaon's maximum security prison, which incarcerates Autobot prisoners of war and a constantly tortured Zeta (showing off Soundwave's sadistic side). Autobot troopers Bumblebee, Sideswipe, and Optimus get themselves arrested so they can escape and rescue Zeta. After Soundwave orders the execution of the three, they put their plan into action and head to Zeta. However, Soundwave arrives first and fights them with the help of his minicons. Soundwave is later beaten and is forced to retreat, never seen again (but he is somewhat successful as Zeta later dies from his wounds).

Fall of Cybertron
The Autobots realize the Decepticons are too powerful and the core is too damaged to maintain life, so they are forced to escape on the Ark, a large cargo ship headed for a mysterious black hole. Using the city sized Transformer Metroplex, the Autobots viciously murders Megatron by crushing him into several pieces. Starscream then finally fulfills his dream and becomes the supreme commander of the Decepticons. However, Soundwave, unsatisfied with the new rank change, goes into his workshop and completely rebuilds his former leader with his remains, catching him up on Starscream's betrayal. Megatron, enraged, barges out of the workshop, beats Starscream, and takes back his place as the leader.

After Trypticon, the Decepticon's ultimate weapon, is defeated, Soundwave rebuilds the useless Transformer into a large fighter ship called the Nemesis to rival the Ark. Later, when the Autobots are a few miles from the black hole, the Nemesis soars by, beginning a final war between the two ships. Megatron orders Soundwave to lead the first assault, so he hops on a tentacle-like cable launcher and rides it all the way over to the enemy ship. He uses his minions to destroy the Ark's defense ammo, but is sucked into the black hole before anymore damage can be done, along with every other Decepticon and Autobot who resided in the two ships.

Trivia

 * As aforementioned, Soundwave is usually portrayed by Frank Welker, who voiced an uncountable amount of characters and animals, some of which are villainous, such as Megatron and Doctor Claw.
 * Another notable fact is that Welker voices Soundwave the exact same way he portrays the just mentioned Doctor Claw, however the voice has an extremely heavy coat of artificial monotone and echo. This can be seen in certain errors of the show where Soundwave speaks without his ominous echo and sounds identical to Claw.
 * Though Soundwave has been portrayed as emotionless, in almost all incarnations, he has been proven that he somewhat loves and cares for his Minicons, as he's lovingly petted Laserbeak and Ravage several times.
 * Jeff Bennett, his voice actor in the Animated Series, also played the Jew Producer and the Joker in The Brave and the Bold.