New 'Transformers One' trailer reveals the root of Optimus Prime and Megatron's rivalry

Every epic rivalry has a tragic backstory explaining how close friends became mortal enemies and the ever-expanding universe of the " Transformers " is no different, as " Transformers One " rolls out this September as the first all CG-animated movie from the multi-billion-dollar franchise .

"Transformers One" hails from Academy Award-nominated director Josh Cooley ("Toy Story 4") and offers up a compelling origin tale of Orion Pax, a.k.a. Optimus Prime (Chris Hemsworth), and D-16, a.k.a. Megatron (Brian Tyree Henry), and their complicated history on planet Cybertron three billion years prior to the core "Transformers" narrative. Also included in this all-star vocal cast are Keegan-Michael Key (B-127 a.k.a. Bumblebee), Scarlett Johansson (Elita-1), Laurence Fishburne (Alpha Trion), Jon Hamm (Sentinel Prime), and Steve Buscemi (Starscream).

A new "Transformers One" trailer and trio of extended clips were revealed on Thursday for an adrenalized Hall H audience at the "Transformers One" panel at San Diego Comic-Con by Cooley, Hemsworth, Henry, Key, and veteran "Transformers" producer Lorenzo di Bonaventura. The convention's sneak peek and Q&A presentation showcased fresh footage of the conflict that led to the fractured relationship between Orion Pax and D-16 and the rise of the dreaded Decepticons. If you need a primer on the "Transformers" franchise, check out our guide to the Transformers movies in order , and see our takes on the T ransformers films ranked worst to best .

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"'Transformers' got me into animation. I wanted to be an animator because of 'Transformers,'" Cooley told the packed crowd. "The thing that got me really excited about this idea was that it's characters that we know as enemies, but seeing how they became enemies was fascinating. First thing, I read the script, I said, this is completely different. I've never seen this before."

Produced by Paramount Animation and Hasbro, "Transformers One" also has the distinction of being the first animated "Transformers" film since "Transformers: The Movie" had "the touch" back in 1986. The animation style for this project has a gorgeous color palette and attractive sheen that immediately immerses you in the turmoil of Cybertron by fusing both past and present design aesthetics of these familiar robots in disguise.

"We did our best to pull them apart and then try and reassemble them, which is quite challenging," Hemsworth recalled during the panel regarding his childhood associations with Transformers toys. "We all failed, actually. We couldn't reassemble any of them."

'Transformers One" charges into theaters on Sept. 20.