Clench This symbol was worn by Clench and his team in Kaon's illegal pitfights prior to the Great War. After Megatron replaced Clench as team captain he retained the symbol for a time before developing the Decepticon insignia as his team emblem.
Security Services This symbol is used by the Autobot Security Services crew operating under Sentinel Prime and was seen on the flags draped over the coffins at the state funeral of operatives Fastback and Bumper.
Senate-related symbol This symbol was worm the crew of Senator Decimus' ship, as well as by Ratbat during his senatorial days.
The War Within
Emirate Xeon This symbol appeared on the helmet of the departed politician Emirate Xeon.
Autobot It seems likely that in the real world, the Autobot symbol was derived from a stylized drawing of Prowl's toy's head. In the Marvel Comics continuity, it was known as the "Autobrand" and was seemingly based on the face of the Last Autobot. In the original animated series, it was a mark of the Quintesson slave brand.
The Autobot symbol as it appeared on Generation One toy packaging.
Decepticon It seems likely that in the real world, the Decepticon symbol was derived from a stylized drawing of Soundwave's toy's head. It has no given origin in either comic or cartoon, but in the latter, it presumably has the same origin as the Autobot symbol. In the live action movie continuity, it was based on blurred image of the Fallen.
The Decepticon symbol as it appeared on Generation One toy packaging. Note the bevelled detail in the center of the crest at the top - the model sheet of the symbol created for the G1 cartoon based on this version misinterpreted it as a third spike, and it appeared in the show rendered in this manner almost universally.
Cybertron Guard This symbol represents the Decepticons under Shockwave's command charged with Cybertron's security. It was retroactively named in 2007 by TakaraTomy's World of the Transformers website, but unnamed in its original context. Divide and Conquer
Wreckers This symbol was used by the Wreckers in the 3H Wreckers/Universe comics, and debuted in 2001. It is uncertain if prior incarnations of the team used this insignia or if it came into use after the signing of the Pax Cybertronia.Departure
Autobot The G2 Autobot symbol seems clearly based on Optimus Prime. In the Marvel Comics continuity this change may have occured since the Last Autobot had come and gone.
Decepticon The G2 Decepticon symbol seems to be a stylized, updated G1 Decepticon symbol. Bludgeon's Decepticons adopted this symbol around 1991, apparently unaware it was also being used by the Cybertronian Empire that they would soon encounter.
Cybertronian This symbol was used by Jhiaxus's Cybertronian Empire, who considered themselves neither Autobot nor Decepticon.
These symbols appeared on the walls of a transwarp shunt room used by Magmatron in IDW's Beast Wars: The Gathering. Although never explicitly stated, they apparently denote the original Predacon combiner team.
Takara used this symbol to represent the Combatron (Decepticon in Robots in Disguise) sub-group in Car Robots — it's an upside-down Generation 2 Autobot symbol, which had been molded into the Black Convoy toy, a redeco of Generation 2Laser Optimus Prime. The Hasbro version removed them and used the traditional Decepticon symbol. Though it can be briefly seen in the anime, this symbol does not "exist" in the English version.
Mini-Con This symbol hints at the origins of the Mini-Cons, in that the "M" is echoed in Unicron's face, with the border representing the planet-eater's orbital ring.
For the 2007 movie, the Autobot and Decepticon factions were rendered in the steel gray seen below. Additionally- the Autobot and Decepticons were strongly associated with the colors blue and red, which led to the Autobot symbol appearing in blue in multiple media. Nonetheless, the 'official colors' of said symbols remains red and purple.
Autobot Changes include slanted eyes, slanted top, and the forehead hole having its high edge straightened
Decepticon Here the eyes are now smaller and more diamond shaped, whereas the original version had triangular eyes.
Sector Seven A Secret organization on earth that is trying to save humanity from the Autobots and Decepticons.