In the (US) G1 series, there'a handful of characters introduced, be it recurrent, regulars or one off. I hope one day, Hasbro/Takara (and 3rd party companies, of course) will be able to release all the cast together with G1 Japan (Headmasters, Masterforce, Victory) and all comic continuities.
Here's basically the cast of the US G1
Season 1
Autobots
- Optimus Prime (Classics/Henkei Line)
- Bumblebee (Classics/Henkei Line)
- Jazz (Reveal The Shield/United Line)
- Windcharger (Generations/United Line)
- Wheeljack (Generations/United Line)
- Trailbreaker (Generations 3.0 Line)
- Sunstreaker (Universe 2.0/Henkei Line)
- Jetfire (Classics/Henkei Line)
- Sideswipe (Universe 2.0/Henkei Line)
- Ratchet (Universe 2.0/Henkei Line)
- Prowl (Universe 2.0/Henkei Line)
- Mirage (Classics/Henkei Line)
- Ironhide (Universe 2.0/Henkei Line)
- Huffer --> Waiting for a proper version, iGear wasn't my cup of tea
- Hound (Universe 2.0/Henkei Line)
- Gears --> Waiting for a proper version, iGear wasn't my cup of tea
- Cliffjumper (Classics Line)
- Brawn --> Waiting for a proper version, iGear wasn't my cup of tea
- Bluestreak (Universe 2.0/Henkei Line)
- Grimlock (Dinobots) (Classics/Henkei Line)
- Snarl (Dinobots) --> Will HasTak take the challenger? Or Toyworld would release theirs?
- Slag (Dinobots) --> Will HasTak take the challenger? Or Toyworld would release theirs?
- Sludge (Dinobots) --> Will HasTak take the challenger? Or Toyworld would release theirs?
- Swoop (Dinobots) --> Will HasTak take the challenger? Or Toyworld would release theirs?
Decepticons
- Megatron (Classics/Henkei/United Line)
- Starscream (Classics/Universe/Henkei/United Line)
- Soundwave --> Still finding the best version
- Thundercracker (Generations/Henkei Line)
- Skywarp (Classics/Henkei Line)
- Shockwave --> Will HasTak take the challenger? Or Voyager-sized Quake Wave?
- Laserbeak --> Still finding the best version
- Ravage --> Still finding the best version
- Frenzy Rumble (Generations/United Line)
- Reflector (Perfect Effect Scouting Force PE-11)
- Kickback (Insecticons) --> Shouldn't have sell Fansproject Causality 01-03
- Bombshell (Insecticons) --> Shouldn't have sell Fansproject Causality 01-03
- Shrapnel (Insecticons) --> Shouldn't have sell Fansproject Causality 01-03
- Mixmaster (Constructicons) (TFC Hercules Project)
- Bonecrusher (Constructicons) (TFC Hercules Project)
- Long Haul (Constructicons) (TFC Hercules Project)
- Scavenger (Constructicons) (TFC Hercules Project)
- Scrapper (Constructicons) (TFC Hercules Project)
- Hook (Constructicons) (TFC Hercules Project)
The list might be incomplete, just a basic reference