8. Transformers: The Last Knight
Even though most Transformers films aren't great, it was awesome for fans to see Optimus Prime, Megatron, and Soundwave in live-action.
But there is one guy that the rabid fan-base have been dying to bear witness to on the big screen.
Unicron. Considering this malevolent android can transform into a planet, it's no surprise he's the biggest and most powerful Transformer. Because of Unicron's unequalled might, it would be a dream come true to see the Autobots and Decepticons forced to ally to face him.
However, we had to wait until the fifth movie, Transformers: The Last Knight, before the world-consuming robot was finally mentioned. (Director, Michael Bay, thought it was more important to incorporate Wheelie and Devastator's balls into the films before incorporating the coolest Transformer ever.)
The film's antagonist, Quintessa, mentions how Unicron resides in Earth's core and she must drain the planet to destroy him. Even though Quintessa is seemingly defeated in the climax, she reappears in the stinger, admiring Unicron's horns, which have penetrated the Earth's surface.
Sadly, this was the first live-action Transformer film to bomb, causing the Unicron story arc to be firmly placed on the back burner.