Tengen Toppa Gurren Lagann

Tengen Toppa Gurren Lagann (天元突破グレンラガン) is the titular mecha of Gurren Lagann. In the TV Series by 8Dsuke_Fujishima, it is the strongest mecha, however, the movies give that title to the Super Tengen Toppa Gurren Lagann.

History
By combining his own Spiral Energy with his comrades', Simon created the ultimate entity, the titular Tengen Toppa Gurren Lagann (literally means "Heaven-Piercing Gurren Lagann") in the final battle against the Anti-Spirals. Not actually a mecha at all, it a mass of materialized Spiral Energy on the scale of a galaxy. Though being similar to the Gurren Lagann, its design is overall very different from other mecha in the series, its armor being made up of red skulls bound together by Spiral Energy that burns continuously from its core, giving it the appearance of Team Dai-Gurren's emblem. Each of its many faces has one cockpit containing: Simon and Nia being the head, Viral the torso and the rest of Team Dai-Gurren in the limbs and joints placed in Lagann-style cockpits. Its abdominal mouth is clenched onto the head of the Lazengann, containing a fully resurrected Lordgenome. It has been confirmed in the data books that the Tengen Toppa Gurren Lagann is 10 million light years in height. This makes it roughly one hundred times the size of the Milky Way Galaxy, and also makes it the largest mecha seen in anime to date, however in the movie adaption it was dwarfed by the Super Tengen Toppa Gurren Lagann, which it fit in the mouth off.

Tengen Toppa Gurren Lagann draws jointly on abilities from its many pilots, including Simon's drills, Yoko's rifle, Viral's swords and so on. The actual limit of the mecha's abilities is immeasurable, as it gains an infinite amount of power depending on the pilots' will to win. At points, Tengen Toppa Gurren Lagann and the Anti-Spirals' Granzeboma fight at forces equal to the Big Bang, the battle being so intense it was shown to rip holes through various dimensions showing that the power of each was on a God-like scale. This is furthered by the fact that they can alter the fundamental laws of reality, such as altering probability and creating matter out of thin air (which is no small feat even by the series' own standard, as the various drills and weapons materialized are larger than most small galaxies).

Trivia

 * Tengen Toppa Gurren Lagann bears a striking resemblance to Super Robot Wars/Taisen Original Generation's Persoenlichkeit. It is quite possible that Tengen Toppa Gurren Lagann is based of Persoenlichkeit, due to the reason that Gainax also participated in many productions of Super Robot Wars/Taisen.
 * Theoretically if the Tengen Toppa Gurren Lagann is 10 million light years across, it would mean that its eventual battle with the equally large Granzeboma would last several billion years, considering that nothing can exceed the speed of light. This would mean that swinging an arm alone might be a feat that would traverse several million light years, which will require the same number of years in real time, to execute. However, since relativistic physics are taken into consideration, it would mean that the Tengen Toppa Gurren Lagann experiences severe time dilation effects that would theoretically make what seems to be a billion years last only several seconds, if the battle occurs at near light speed. Thus, the battle shown might be a condensed event that occurs not from the observer's objective time frame, but from the Tengen Toppa Gurren Lagann's subjective time frame. If the battle really took several billion years though, in actuality, the galaxies should dwindle in terms of their stellar intensity due to the end of solar rebirth cycles caused by the heat death of the universe, assuming a situation whereby a big crunch does not happen.
 * Also, if the battle between the Tengen Toppa Gurren Lagann and the Granzeboma really did occur at such an immense inter-galactic scale which also caused several Big Bang level explosions to occur while they were hurling entire gargantuan galaxies at each other, the number of civilizations that they might have destroyed in the crossfire might have been several billion, assuming that a typical galaxy holds about 1 million intelligent civilizations. If each civilization has an upper bound of 1 million people (which will be destroyed by the anti-Spirals if that is reached), the number of casualties in the "duel" between the two giant battle bots might have not just been 1 (the death of the Anti-spiral collective consciousness), but several thousands of trillions. If the battle really did last for several billion years, it would give ample time for more intelligent races to evolve, thereby increasing the number of such civilizations by up to ten-fold, making the number of casualties even more staggering.