The live-action Transformers movies were known for featuring radically different designs for the iconic Cybertronians on display. One egregious example was Decepticon leader Megatron, whose aesthetic dramatically changed with each movie. In fact, one film was originally going to give him a far more bestial alternate mode.
Transformers: The Last Knight finally presented a Megatron resembling his original Generation 1 design. However, the final film didn't feature his intended alt-mode of a ferocious dragon. This decision not only robbed the movie of a fitting design schematic but also kept Megatron from homaging another popular incarnation of the villain.
The Last Knight Almost Had Megatron Transform Into a Dragon
As revealed by artist Josh Nizzi (who worked on the film), The Last Knight's design for Megatron underwent several changes. That was just another day for the villain, who never had a consistent design throughout the series. For instance, his initial look in the first Transformers movie was almost wholly unrecognizable, and it was only changed to somewhat resemble Generation 1 by the time of the theatrical release. The Last Knight finally gave him something resembling his old "bucket head" design and the familiar fusion cannon on his right arm. It also gave him a Cybertronian jet mode in homage to the series' first live-action film, though that wasn't always the plan.
As seen in some of Nizzi's art, Megatron's alternate mode was going to be a giant robotic dragon. That makes a lot of sense in two ways, especially given the designs of that film and the one before it. In the fourth and fifth Transformers films, a general fantasy aesthetic was given to Optimus Prime, a few other Autobots and their Decepticon enemies. Thus, Megatron being a dragon this time was the logical fruition of his arch-enemy being a mighty knight. It would have also explained why his robot mode had no signs of the jet mode that he initially had. Not only was this missed opportunity an incredibly cool concept, but it also would have fallen in line with the franchise's history.
The Fifth Transformers Movie Nearly Emulated Beast Wars' Third Season
In the 1990s animated series Beast Wars: Transformers, the Autobots and Decepticons were replaced by the Maximals and Predacons, their descendants. One of these villains was a new version of Megatron, the likes of whom was inspired by his Decepticon predecessor. In order to change the history of his oppressed subgroup of Cybertronians, Beast Megatron attempts to use Transwarp technology to go back in time and assassinate Optimus Prime. In response, Prime's descendant Optimus Primal briefly houses his spark and the Matrix of Leadership, becoming "Optimal Optimus." Megatron tries to emulate this by similarly absorbing the spark of the original Megatron, which mutates him into a mighty Transmetal 2 dragon.
That would've been somewhat emulated had The Last Knight maintained this alternate mode for Megatron, especially given the events of the previous movie. In Age of Extinction, Megatron's corpse turned into Galvatron, with Quintessa restoring him to his original state in the next film. The idea of Megatron's body "going back to the original version" and gaining a dragon form is similar to what happened to Beast Megatron. Unfortunately, the homage wasn't meant to be, and the movies are only now adapting the cast of Beast Wars. With Transformers: Rise of the Beasts on the way, however, it's possible that Beast Megatron himself could show up in some form.