Starscream

Second in command of the Decepticons. Likes video games. Continues to challenge Megatron for leadership of the Decepticons, thinking himself superior to the others, but never seems to succeed. Everytime Megatron comes back he has relinquished command. He's vain, egotistical and in general, a huge jerk always at odds with the other decepticons, especially Megatron.

Thundercracker

The seemingly more mature of the Seekers (Thundercracker, Starscream and Skywarp) and probably having more experience, Thundercracker has to unfortunately endure being bossed around by both Starscream and Megatron. He has a mellow composure though, which is probably the only reason why he hasn't gone insane.

Skywarp

Skywarp is the jock out of the three seekers. He follows Megatron's orders perfectly, enjoying the mischief and havoc caused by it. He's at constant odds with a few of the Decepticons, Starscream being one and a mini cassetticon named Rumble, being the other. Of the three seekers, he also seems to have slightly less intelligence, although manages to mess up less than Starscream. He also has the ability to teleport, but if only he used it more often. Usually if he's hit he's often crashing into Thundercracker, taking them both out at once.

Shockwave

Guardian of Cybertron in Megatron's absence for 4 million years. Shockwave is extremely loyal to Megatron, and has a knack for contacting him without Megatron's permission, often leading to unwanted communications.

Soundwave

Soundwave is the absolutely most useful Decepticon in the entire galaxy. He produces energon cubes for which to store the energy the Decepticons collect as well as carries within him a miniature army called the Cassetticons (that Rumble is one of). He is also blindlessly loyal and never fails Megatron. He also has a really cool voice.

Rumble

Rumble is a small little Decepticon (Roughly human-sized) who thinks big. Actually, he never seems to notice how small he really is. He is a Cassetticon that springs from Soundwave when needed. Usually though, it seems he is always needed, as Megatron seems to bring him on every single mission they carry out. His arms turn into pile drivers, giving him the ability to cause localized earthquakes, tearing up the ground. Perhaps because he is in a way attached to Soundwave that he is also one of the only Decepticons Megatron allows to offer glib remarks at the Decepticon leader's orders.

Reflector

Is Reflector three robots that can turn into one? Or one robot that can split into three? Reflector is kind of a mystery, especially since he's probably average sized for a transformer (though not nearly as large as the seekers) yet it takes three of him to turn into a small single lens camera that Thundercracker uses to take pictures. His lens have the ability to focus closely on very far objects, which is useful maybe two or three times so far in Decepticon history. Don't worry Reflector - everyone still respects you.

Astrotrain

Astrotrain is part of a unique family of transformers known as the
"Triple Changers." He has the ability to transform into a train, or a space shuttle. The Decepticons use him as a transport from planet to planet, usually leaving him stranded with little energy while they go off and do their misdeeds. He's usually complaining, but lacks the initiative to really do anything on
his own.

Laserbeak

Laserbeak is perhaps Megatron's favourite Decepticon. (Next to Soundwave.) ...Although part of his charm might be that he is one of Soundwave's cassetticons. He acts as a spy for the Decepticons and has the ability to record conversations and visuals. He is quite a nuisance to the Autobots.

Swindle

Swindle would sell you his own components - if he thought he was getting a good deal for them. Always wheeling and dealing this crafty Decepticon is always looking out for the best offer, and will deal indiscriminately regardless of faction if it is to be to his advantage. He'll always look out for himself first.