RETURNING AUTOBOTS
Optimus Prime - The Autobot leader. He retains his alternate mode of a blue Peterbilt truck with red flame decals. He is seemingly killed by Megatron, but is brought back to life after receiving the Matrix of Leadership. He then uses parts from Jetfire to destroy the Harvester and fight Megatron and The Fallen. He manages to wound Megatron and the overpowers and kills The Fallen.
Bumblebee - The Autobot who befriended Sam and disguises himself as his fifth-generation Chevrolet Camaro. Bumblebee's voice is still healing and he still uses radio soundbites to express some of his emotions.
Ironhide - The Autobot weapons specialist who transforms into a GMC Topkick. He helps Optimus bring down Demolisher in the beginning of the film.
Ratchet - The Autobot medic who transforms into a search and rescue Hummer H2.
NEW AUTOBOTS
Arcee - A female Autobot who transforms into a pink Ducati 848 motorcycle, she and her sisters were seen in both teaser chasing after Sideways. Only Arcee is addressed by name in the movie, however the others are given names in the toyline.
Chromia - Arcee's sister, she transforms into a blue Suzuki B-King 2008 motorcycle.
There is a third purple MV Agusta F4 motorcycle, it is unknown of who she is, some people believe it could be Firestar or Moonracer. This purple one is seen getting hit by fire from Decepticons in the final battle after telling Sam that they would cover his path to Optimus; but is does not appear that she was killed.
Mudflap and Skids - Also known as The Twins, They start the film by combining into a pink and white ice cream van. Skids makes the front end of the van, while Mudflap makes the back. These Autobot infiltrators later on upgrade to a green Chevrolet Beat (Skids) & a red Chevrolet Trax (Mudflap). Mudflap is very hyperactive, while Skids believes himself to be the smarter of the two and tries to come across as mature, but nevertheless appears unable to keep quiet.
Wheelie - A blue radio-controlled toy monster truck. Wheelie initially serves the Decepticons, but because he is frightened of them he joins the Autobots.
Jolt - A blue Chevrolet Volt. Being an electric car, Jolt's weapons are a pair of electric whips. He was a last-minute addition to the cast as General Motors, the film's car supplier, wanted to promote the Volt. The writers had already wanted to include the car in the script before the Writers Guild strike, so they had to work out a character that would fit well within the Autobot team afterwards and convince Bay to approve the addition. Jolt has very little screen-time in the movie; his only prominent moment being when he uses his electric whips to help Ratchet attach Jetfire's body parts to Optimus.
Sideswipe - A silver Chevrolet Corvette Stingray Concept. He is an expert fighter with his swords and tries to get in close with his opponents. After Arcee and her sisters failed to stop Sideways from escaping, Sideswipe arrives and swiftly slices the Decepticon in half (whilst he is still in vehicle mode).
Jetfire - A self-described mercenary, an ancient former Decepticon who transforms into a SR-71 Blackbird. His wounds and age have made him choose to become an Autobot. He sacrifices his life so his parts can be combined with Optimus to give him the strength needed to destroy The Fallen.
RETURNING DECEPTICONS
Megatron - The Decepticon leader. Killed and thrown into the Laurentian Abyss(along with Blackout, Brawl and Bonecrusher) in the first film, he is resurrected by the Constucticons (one of which is sacrificed for the process) and The Doctor as a Cybertronian tank that can also fly. He has become stronger as a result of absorbing the Allspark fragments that originally killed him. When reviving the character, the writers chose not to rename him Galvatron so as to not confuse the general audience. Megatron survives the events of the film; retreating into space with Starscream after The Fallen is killed. Megatron reluctantly complies with this, whilst as the same time noting that ''this isn't over''. The comic book adaption shows him returning to the Nemesis and awakening more Decepticons from stasis.
Starscream - The Decepticon air commander who transforms into an F-22 Raptor. He flew into space at the end of the previous film, and now returns bearing Cybertronian symbols on his body due to his coronation. He led Megatron's armies in his absence, but is relegated to second in command when his leader returns to life. He again, survives the events of the movie; suggesting himself to Megatron (in a manner very reminiscent of his G1 counterpart) that they retreat after The Fallen is killed.
Scorponok - A metallic scorpion-like minion of Blackout, he dissapeared into the sands and losing his tail after a battle with Lennox and his team in the first movie. Scorponok hid in the desert and repaired his tail. He reappears in the final battle in which he attacks and badly wounds Jetfire, before he is destroyed by the ancient Transformer.
NEW DECEPTICONS
The Fallen - One of the original thirteen Primes who created the Transformers, he was banished and stripped of his name for his willingness to destroy life in the search for new Energon. It is he who corrupted Megatron into forming the Decepticons. His toy transforms into a Cybertronian aircraft but he only appears as a robot in the movie. He is first seen in the movie recovering from his long imprisonment aboard the Decepticon ship, the Nemesis. He instructs Megatron to find Sam Witwicky and also tells him that only a Prime can defeat him; and that Optimus is the last one left. The Fallen regains his strength after Optimus is seemingly killed by Megatron and heads to Earth with more Decepticons. After arriving in Egypt, he attempts to power up the recently revealed Harvestor, but is stopped by Optimus Prime, who fights and kills him.
Soundwave - Megatron's intelligence officer. He appears as a Cybertronian spy satellite that exploits the military's own communications network, coordinates the Decepticon offensive, and deploys Ravage. The Soundwave toy has robot, jet and satellite capabilities, but he only appears as a satellite in the movie.
Ravage - A minion that resembles a large one-eyed jaguar that transforms into a missile. Ravage is one of the minions of Soundwave, and is launched into the sea near NEST's base to retrieve the Allspark shard. The original growls and snarls by Frank Welker from the G1 series are being used in Ravage's new incarnation.
He is later ripped apart and killed by Bumblebee during the climax in Egypt, after attempting to attack him from behind.
Grindor -This Decepticon transforms into a MH-53 Pave Low, a robot greatly similar to Blackout from the 2007 movie. Grindor shares both Blackout's MH-53 Pave Low helicopter alternative mode, and his robot model, being only differentiated by a lighter paint job and different head model, he was mistaken to be Blackout in the movie but since Blackout was not seen resurrected, its safe to assume its Grindor, his name is Grindor in the toyline but in the movie his name was never mentioned.His role is very short, as he is the one that takes Sam and his friends to Megatron and the Doctor. He is killed by Optimus during the forest fight.
Sideways - A silver Audi R8. He is hiding with Demolishor in Shanghai, China until he is discovered by the Autobots. He was shown crashing through a building and into an alley, before transforming and racing away from Arcee and her sisters. He is destroyed by Sideswipe in the beginning of the movie.
Demolishor - A red Terex O&K RH 400 hydraulic mining excavator, who is the protector of a small Decepticon community in Shanghai. shown in both the TV spot and teaser trailer smashing through an overpass in China, while another shot in the teaser trailer shows him Transforming into his robot form, along with shots of him swatting helicopters out of the sky. He is killed by Optimus and Ironhide in the beginning of the movie, before his death his last words are "The Fallen shall rise again" after which Prime shoots him one final time in the head.
''Constructicons / Devastator'' - A 46 feet (14 m) tall (hunched over) massive robot formed by several combining construction vehicles, who walks in a four-legged fashion resembling a gorilla. He is physically unable to stand upright, but would be 100 feet (30 m) to 120 feet (37 m) tall if he did. Gears and turbines in his body produce a suction vortex in his mouth which devours machinery and debris. He also uses grappling hooks to climb the giant pyramid in the final battle because his size prevents him otherwise.
In the first film, the name "Devastator" was mistakenly given to Brawl, a tank (Brawl may have called himself 'Devastator' because he thinks it sounds more threatening - much like Michael Bay's reason for giving him that name). Long Haul, Rampage, Mixmaster and Scrapper are seen heading down to the bottom of the ocean in hunt of Megatron's corpse, ultimately reactivating their fallen leader. One of the robots is cannibalised for parts to achieve this, the identified robot was confirmed as Scrapper. Not all of the Constructicons are seen in robot mode.
Mixmaster - The leader of the Constructicons. He transforms into a black and silver Mack cement mixer truck, forming the head. There appears to be 3 Decepticons who share the same form and resemblance that is Mixmaster. One of them is brought to life on a ship along with Scrapper, Longhaul, & Rampage. The other one is destroyed when Devastator is hit by the rail gun while on top of the pyramid, and the third is killed by Jetfire while he is in his "battle" mode.
Rampage - A yellow Caterpillar D9 bulldozer who forms the left leg. There appears to be 2 Decepticons with the same form that is Rampage, however the one that is referred to as Rampage, is the one who holds Sam's parents hostage and is soon after defeated by Bumblebee.
Scrapper - A yellow Caterpillar 992G scoop loader who forms the right arm. Again, their appeares to be 3 Scrappers, One of which was killed by his fellow constructicons brutally cannibalising his parts when Scalpel demanded more parts for rebuilding Megatron in the bottom of the Laurentian Abyss. In the film's climax, another Scrapper in vehicle mode is seen merging with the other six Constructicons to form Devastator; this one is killed when Devastator is destroyed by an experimental rail gun. The individual Scrapper is seen pursing Sam and Mikaela (in his robot mode) in Egypt during the final battle, he is killed with Long Haul after some fighter jets drop bombs on them.
Overload - A red articulated dump truck that forms the torso along with Scavenger.
Scavenger - A red Terex O&K RH 400 hydraulic mining excavator, closely resembling Demolishor. He forms the torso along with Overload.
Hightower - A yellow Kobelco CK2500 crawler crane that forms the left arm.
Long Haul - A green Caterpillar 773B dump truck, which forms the right leg. Long Haul's individual robot mode was designed by freelance artist Josh Nizzi as fan art of the original character. The fan art impressed Bay enough to hire him on to the film. There appears to be 3 Decepticons who share the same form and resemblance that is Longhaul. One of them forms the right leg of Devastator, another is brought to life on a ship along with Mixmaster, Scrapper, & Rampage, while the other was fighting the Autobots in the final battle in egypt. He is later killed along with Scrapper after fighter jets drop bombs on them.
*It should be noted that when it comes to the Constructicon toys that combine to make Devastator; for some reason, Overload is not Included. Only Mixmaster, Rampage, Scrapper, Scavenger, Hightower & Long Haul.*
Scalpel - A small, spider-like robot who turns into a microscope. He is a medic and scientist equipped with tools he is seen using to resurrect Megatron and extract All Spark data from Sam's brain. The other Decepticons call him "The Doctor". The packaging of his Scout-Class figure details he is skilled in dissecting and rebuilding almost any living organism. He is destroyed when Optimus and Bumblebee arrive to rescue Sam, Mikeala and Leo.
Alice - A Pretender who stalks Sam. She is portrayed by Australian actress Isabel Lucas Her origins are unknown in the movie, but the tie-in adaptations show her copying the appearance of an animatronic Alice in Wonderland model. Beneath her Pretender shell she is a dangerous humanoid robot with several weapons. She is killed by Mikela, who crashes into her with her car.
Reedman - Name not known. They are hundreds of tiny ball-shape insect size Decepticons that may be Insecticons. It turns out to be a robot formed by some nanobots dropped by Ravage, and can combine to form a cat-like robot similar to the first movie's Frenzy. The movie names this cat-like form "The Thin Man" or "Thinman," variously, his name is revealed to be Reedman.
Insecticon - Seen very breifly as a spy working for the Decepticons, He discovers where Sam and Mikela are hiding in Egypt, only to be ripped in half by Sam, which ultimatly tips Starscream off to their postion.
There will be other minor robots, including some robots who can transform into weapons and some cooking appliances brought to life by the All Spark shard, including the toaster bot from the Mountain Dew tie-in advert for the first film. There is also a brief cameo of Frenzy. His decapitated head is seen in a jar in Simmons' posession, with Simmons commenting that it is "still radioactive." Also Bonecrusher's vehicle mode from the 2007 film also makes a cameo appearance among the forces in Egypt.
Their are also two Decepticons that look alike (see here). Who they are is yet unknown.
Writers Roberto Orci and Alex Kurtzman have stated that their are ''10 un-named robots in this movie''. Several Decepticons with only Cybertronian forms feature in the movie and the final battle. An un-named Decepticon resembling Bonecrusher also features in this sequence.
Also seen in the movie are Decepticon protoforms (i.e. infant Transformers) aboard the Nemesis, where it is revealed by Starscream that lack of Energon means that they are dying.