The main antagonist mecha from the Turn A Gundam anime series from 1999.
Is notable because it was designed by the legendary American science fiction film designer Syd Mead.
The CONCEPT-X 6-1-2 Turn X was originally going to be the hero mecha of the show, but series director Tomino Yoshiyuki coinsidered the design too "un-Gundamish", so he chose the design as the antagonist robot and made Syd Mead develop another design (which was also kinda "un-Gundamish" in the end...).
Although it is also equipped with the Moonlight Butterfly super weapon, the Turn X is the second strongest Mobile Suit in the entire franchise due to the fact that the Turn A Gundam defeated it not once, but twice.