Insignia

One of the universals across all Transformers continuities has been the use of faction symbols to differentiate members of respective armies, and sometimes even sub-factions within armies.

Generation 1

 * Quintesson


 * Ancient Autobot


 * Ancient Decepticon

(This is a symbol that Shockwave adopted in the G1 Dreamwave comic book. Although Transformers have been split into two races, they are one species, he claims.)
 * Ancient Transformer


 * Autobot (War Within)


 * Decepticon (War Within)

(Used by Ratbat's group in The War Within era)
 * Ultracon

(In G1 Comic continuity the Autobot symbol was based on the face of the Last Autobot. In the G1 Cartoon it was derived from the Quintesson slave brand) 
 * Autobot



(In "Real World" terms it seems likely that Hasbro designers based the Decepticon symbol on the head of Soundwave's toy. In the G1 cartoon the usual 3D detailing of the symbol was interpreted as a third spike in the center of the crest.)
 * Decepticon


 * Optimus


 * Malignus


 * EDC


 * Wreckers

G.I. Joe Crossovers

 * Cobra


 * G.I. Joe


 * Decepticon/Cobra

Generation 2

 * Cybertron Federation

(This symbol was used by Jhiaxus's Cybertronian Empire, who considered themselves neither Autobot nor Decepticon.)
 * Cybertronian



(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.)
 * Autobot (G2)



(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 encoutner.)
 * Decepticon (G2)



Beast Era
(From IDW's Beast Wars comic books)
 * Arachnoid
 * Autobot (Transtech)
 * Blentron
 * Decepticon (Transtech)
 * Dinobot
 * Maximal
 * Maximal (Beast Machines)
 * Moon
 * Mutant
 * Predacon
 * Predacon (G1)
 * Seacon Space Pirate
 * Vehicon

Robots in Disguise

 * Commando

Unicron Trilogy

 * Mini-Con
 * Unicronian
 * Cybertron Defense Team
 * Powerlinx

Others

 * My 1st Transformer
 * Go-bots Autobot
 * Go-Bots "G"