2007 Transformers:
* Megatron (Leader): The main antagonist and leader of the Decepticons. He is a ruthless tyrant who wants to conquer Earth.
* Starscream (Second-in-Command): A treacherous and ambitious Decepticon who constantly plots to overthrow Megatron.
* Blackout: A towering Decepticon who transforms into a helicopter and is known for his brutality.
* Brawl: A powerful Decepticon who transforms into a construction vehicle and is known for his strength.
* Scorponok: A Decepticon who transforms into a scorpion and is known for his venomous tail.
* Frenzy: A small and agile Decepticon who transforms into a motorcycle.
* Bonecrusher: A Decepticon who transforms into a bulldozer and is known for his destructive capabilities.
* Barricade: A Decepticon who transforms into a police car and is known for his pursuit of the Autobots.
* The Fallen: A powerful Decepticon who was the leader of Megatron's faction in the past.
* Sideways: A Decepticon who transforms into a car and is known for his ability to teleport.
* Jazz: Initially an Autobot, Jazz is captured by Megatron and brainwashed into a Decepticon.
2009 Transformers: Revenge of the Fallen:
* Megatron (Leader): Returns as the main antagonist, seeking revenge against the Autobots.
* Starscream (Second-in-Command): Continues his schemes to overthrow Megatron.
* The Fallen (Leader): The main antagonist in this film, seeking to conquer Earth.
* Soundwave: A Decepticon who transforms into a satellite and is known for his communication abilities.
* Devastator: A massive Decepticon formed from the combination of six Constructicons: Scavenger, Mixmaster, Long Haul, Bonecrusher, Scrapper, and Rampage.
* The Constructicons: The individual Decepticons that make up Devastator.
* Rampage: A Decepticon who transforms into a monster truck and is known for his destructive capabilities.
* Ravage: A Decepticon who transforms into a panther and is known for his stealth and agility.
* The Twins: Two Decepticons who are able to shapeshift.
* The Driller: A Decepticon who is able to drill through the Earth's crust.
This list includes the main Decepticons from the two films, but there are other minor Decepticons that appear as well. The Transformers movies have a large cast of characters, so this is just a selection of the most prominent Decepticons.