Generic

A "generic" is the fan-coined, unofficial term for any unnamed background Transformer that is clearly not intended to represent any previously existing and named toy/character. Generics are frequently used to fill out crowd scenes and battles, and often employ repeated standardized designs.

It is rare that a generic gets a speaking part, but it has happened from time to time. However, if the character is given a name they cease to be a generic and becomes a regular old character. Over time, thanks to fans-turned-pro and conventions looking for con-exclusive toys, quite a few generics have made this leap!

Transformers: Prime

 * The Decepticons employ generics in the form of Vehicons which come in two flavors—jet and car.
 * In season 2 and 3, white versions of the Jet type appeared as Seekers, though they were just as generic as their purple brothers.
 * The Decepticon Miners all use the same model, which is very similar to that of a car Vehicon. This model is later altered for the bounty hunter Shadelock.
 * The Vehicons featured in season 2 of Robots in Disguise reprise their Prime models. This time, their color schemes vary amongst themselves.
 * The Insecticons also shared a character model, with Hardshell only being distinguished by his facial scars.
 * The good guys in Prime also have generics, as virtually all of the human soldiers seen use the same model.

Transformers: Robots in Disguise

 * The Caretaker Mini-Cons featured in Robots in Disguise, including Toolbox and Cinch, all share the exact same model as Fixit.
 * The Skunkticons all share the same model as their leader Malodor.

Decepticon Island inhabitants
Besides Vehicons, Glowstrike and Scorponok's crew of Alchemor escapees includes a host of generics recolored from existing models, including several originally from Prime:
 * A black, bright-green and teal Insecticon. The colors match Bombshock's Cyberverse toy, but are laid out entirely differently.
 * Two Cyclones, one purple, one black-and-green. They both share the same body-type as Backtrack, Ransack, and Bounce.
 * An orange and blue look-alike of Airachnid (sans spider legs).
 * Two Chompazoid guards, one burgundy, one light brown. They have different jaws than Underbite, lacking, well, underbites. Many Chompazoids were present during the Bee Team's raid on Decepticon Island.
 * There are also Sharkticons identical in design to Hammerstrike and Ragebyte, including one sporting a color scheme (and eyes) more in line with the species' G1 counterparts.

Trivia
With help from Robots in Disguise showrunner Adam Beechen, the following minor Transformers have had their names revealed on his website:
 * Scratch as the proper identity of the cat-like Decepticon Windblade defeats in "The Buzz on Windblade".
 * Razorhorn as the identity of the Insecticon bounty hunter featured in the latter half of the post-Season 2 mini-series.
 * Goldgear as the identity of the Activator Mini-Con who successfully steals Strongarm's Decepticon Hunter after Hi-Test failed to do so.