Transformers 2 Decepticons

* Hugo Weaving voices Megatron, the Decepticon leader. Killed and thrown into the Laurentian Abyss in the first film, he is resurrected by his legions with cannibalized parts as a Cybertronian tank. 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.

* Charlie Adler voices Starscream, the 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 and commanding a new Decepticon army. Orci confirmed he will have more dialogue. Chris Mowry, writer of the comic book prequels, stated Starscream differs from his 1980s incarnation because "His motivations are more for the species. He's definitely at odds with what Prime and Megatron have been doing. He thinks that they’ve both been consumed with greed, for their own selfish reasons, but as he finds out, his plans start to fall through as he’s kind of becoming overwhelmed with the same greed that they had." However, Orci explained that during post-production, dialogue additions edged Starscream closer towards his 1980s counterpart.

* Soundwave, Megatron's communications expert and his most loyal soldier. Bay expressed interest in getting Frank Welker, Soundwave's original voice actor, to portray the film version. He transforms into a Cybertronian craft with jet and satellite capabilities. The concept artists also designed an Earth form of a Chevrolet Silverado for him to upgrade into, which Orci stated was dropped. In the 1980s toyline, Soundwave's alternate mode was a microcassette player. The filmmakers had tried to work him into the first film twice, and these roles eventually evolved into Blackout (a MH-53 Pave Low helicopter) and Frenzy (who changed into a CD Player and later into a mobile phone). The latter character was particularly thought to be too different from the original.
o Ravage, a minion that resembles a large one-eyed cat.
o A robot resembling Frenzy, but with a cat like face, dreadlocks, and a bird-like beak.

* The Fallen. One of the original thirteen Transformers, the robot known as the Fallen is the one who corrupted Megatron into forming the Decepticons. He is trapped in another dimension and was able to communicate with the Decepticon via an interdimensional window, the distorted effect of which inspired the image the Decepticons use as their insignia. Lorenzo di Bonaventura compared the Fallen to Judas Iscariot. He transforms into a Cybertronian aircraft. The writers selected the Fallen after looking through various cartoons and comics for new characters, because he was the most "elemental" villain. Orci and Kurtzman approached Leonard Nimoy, who they had collaborated on Star Trek with, about voicing the part; Nimoy voiced Galvatron in 1986's The Transformers: The Movie and is also married to Bay's aunt Susan. Orci said Welker might take on the role due to "fan outcry".

* The Constructicons / Devastator, a 100 to 120 feet tall warrior formed by several combining construction vehicles. The name Devastator was mistakenly given to Brawl, a tank, in the first film. The name Bonecrusher, who was one of the Constructicons in the 1980s and Transformers: Universe, was also used for a Decepticon killed in the first film. The original Constructicon names Scrapper and Mixmaster appeared as drone units in the Transformers movie video game.
o Demolishor, the Terex O&K RH 400 Hydraulic Mining Excavator seen in the first trailer. He forms Devastator's torso. He is the protector of a small Decepticon community in Shanghai. The character has also been referred to as Scavenger, even in interviews that mention Demolishor. The writers simply called him "Wheelbot".
o Hightower, transforms into a yellow Kobelco CK2500 Crawler Crane and forms the left arm.
o 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.
o Mixmaster, who transforms into a black and silver Mack concrete mixer. He forms the head.
o Rampage, a Caterpillar D9 bulldozer who forms the left leg.
o Scrapper, a Caterpillar 992G scoop loader who forms the right arm.

* Scorponok, Blackout's former partner who resembles a car-sized mechanical scorpion. In the first film he burrowed into the ground after being defeated by the military in Qatar, and lost part of his tail. His tail is restored in the film.

* Sideways, an Audi R8.

* Scalpel/ The Doctor, a small, spider-like robot who turns into a microscope. He is a medic and scientist equipped with tools he uses to torture Sam.

* Isabel Lucas plays Alice, a Pretender who stalks Sam.

Orci hinted the majority of the Decepticons were entirely computer-generated in both robot and alternate modes, which would make it easier to write additional scenes for them in post-production. Lorenzo di Bonaventura said that in total, there are around forty robots in the film, while ILM's Scott Farrar has said it is actually sixty. There will be some robots who can transform into weapons and some cooking appliances brought to life by the AllSpark shard (including the toaster bot from the Mountain Dew tie-in advert for the first film).