Crisis on Infinite Cybertrons

Optimus Prime and Optimus Primal realise their Cybertrons have collided, and so have Star Saber's and Dai Atlas's Cybertrons.

Optimus Prime, of the Live-Action Trilogy universe, and Lio Convoy, of the Beast Wars II universe, encounter one another!

Optimus Prime, of the Animated Universe, and Optimus Prime, of the G1 Universe, meet each other, amongst other Primes.

Autobots and Maximals

 * Optimus Prime: The G1 Version is the main hero. The Optimus Prime from the Shattered Glass universe is the main villain and caused the Cybertrons and Earths to collide. The G1 Prime met all his counterparts, all except this threat.
 * Optimus Primal
 * Star Saber
 * Dai Atlas
 * Arcee
 * Elita-1
 * Hardhead
 * Chromedomw
 * Highbrow
 * Brainstorm
 * Stampy
 * Ironhide
 * Bumblebee
 * Cheetor
 * Rattrap
 * Rhinox
 * Jazz
 * Ratchet
 * Side Burn
 * Rodimus Prime
 * Sentinel Prime
 * Powerglide
 * Ultra Magnus
 * Warpath
 * Seaspray
 * Cosmos
 * Metroplex
 * Tracks
 * Wheeljack
 * Grimlock and the Dinobots
 * Silverbolt
 * Sunstreaker
 * Sideswipe
 * Prowl
 * Bluestreak
 * Trailbreaker
 * Outback
 * Skids
 * Stratosphere
 * Jetfire
 * Chromia
 * Breakaway
 * Getaway
 * Red Alert
 * Longrack
 * Heinrad
 * Cohrada
 * Break
 * Diver
 * Tasmania Kid
 * Bighorn
 * Apache
 * Scuba
 * Overload
 * Drift
 * Roadbuster
 * Whirl
 * Springer
 * Dag Base
 * Guzzle
 * Mirage
 * Inferno

Decepticons, Predacons, and Vehicons

 * Megatron: All of his incarnations met, except for heroic Megatron from the Shattered Glass universe, who betrayed him.
 * Starscream
 * Strika
 * Obisidian
 * Galvatron: Megatron's future counterpart appeared to him alongside the other Galvatrons.
 * Octane and Sky-Byte: Tried to overthrow Megatron.
 * Spittor: Turned into a Maximal and Transfixated as punishment by Optimus Primal.
 * Barricade
 * Blackout
 * Scorponok
 * Sentinel Prime DOTM Version: This Sentinel Prime made a cameo in certain episodes.

Episodes

 * Crisis! (Crisis! Cybertrons Colliding)
 * Earths Collide (Colliding Earths!)
 * Shattered Glass (Behold! The Mirrorverse Villain)
 * WInning Streak! (Win! Optimus Prime and Primal)
 * Inferno (A New Autobot Appears! Inferno)
 * Never Giving Up (Don't Give Up to the Evil Version of Optimus!)
 * Earths Seperated (Shattered Universes! Earths Split Apart)
 * Final Battle (Megatron VS Optimus Prime! The Final Battle!)

Japanese Opening and Ending Themes

 * "Yume wo Dakishimete no Crisis" by MIQ, Eizo Japan, JAM Project, Takayuki Miyauchi, Isao Sasaki, Akira Kushida, Psychic Lover, YAMA-B, Animetal USA, and Mitsuko Horie, among others (opening theme) (sung in multilanguage)
 * "Crisis is Over! My Last Song" by Masato Shimon (ending theme) (sung in english)