Tengen Toppa Gurren Lagann

"Nia: Even when trapped by karma's cycle... Yoko: The dreams we left behind will open the door!

Leeron: Even if the universe stands in our way!

Viral: Our seething blood will determine what will be!

Simon: We'll break through time and space!

Team Dai-Gurren: And defy all who would stop us, to grab hold of our path!

Simon: TENGEN TOPPA GURREN LAGANN!

Team Dai-Gurren: JUST WHO THE HELL DO YOU THINK WE ARE?!?!?!"

- Team Dai-Gurren

Tengen Toppa Gurren Lagann (天元突破グレンラガン) is the titular mecha of the anime. Its design is based on the smaller Gurren Lagann and is its final form in the anime, but the movies give that title to its succeeding form, Super Tengen Toppa Gurren Lagann.

By combining his own Spiral Power with his comrades, Simon created the true titular entity, which he titles, Tengen Toppa Gurren Lagann, in the final battle against Antispiral. Not actually a mecha by traditional means, the Tengen Toppa Gurren Lagann is actually a mass of continuously materialized Spiral Power (similar to the Spiral technique used to materialize Drills) on the scale of a Super Spiral galaxy.

Appearance
Tengen Toppa Gurren Lagann resembles the original Gurren-Lagann, albeit with a more intensely themed appearance. Its armor is covered in various draconic skulls and faces; since the number of total faces is equal to the number of key pilots of the mech, it can be assumed that these are its cockpits. The head wears a more symmetrical version of Lagann's helmet, while the chest face wears a pair of non-functional sunglasses. Its abdominal mouth is clamped onto the Lazengann's head, which Lordgenome can detach and use to create a galactic-scale Lazengann.

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, illuminated by the storm of Spiral Power that burns continuously from its core, giving it the appearance of Team Dai-Gurren's emblem. Of its many faces, the primary "cockpits" contain: Simon & Nia in the head, Viral in the torso, Yoko  in what seems to be either the right shoulder or the right shin, and Leeron  in the left hip. The rest of Team Dai-Gurren are positioned at various points in the limbs and appendages, all operating in Lagann-style cockpits. Its abdominal jaw is clenched onto the head of the Lazengann, containing a fully resurrected Lordgenome.

Size
It has been confirmed in the databooks that the Tengen Toppa Gurren Lagann has immeasurable size and impossible to calculate as the mecha is nothing but a materialized thought, and a higher dimensional entity (It doesn't exactly exist in the physical world).

Its physical size (if existing in physical world) is 1025 times Gurren Lagann's height. But the guidebook is ambiguous on a few details, including Gurren Lagann's height (while the book assumes 5 meters for the Arc and Super Galaxy Gurren Lagann's heights, it's ambiguous if that applies to Tengen Toppa as well) and a potential 10x multiplier (the exact wording being "In traditional Gurren Lagann style it's multiplied by 10", with the past tense implying the mutiplication has already happened). As such, Tengen Toppa Gurren Lagann has four possible heights, ranging from 5.28 billion light years (with a 5-meter Gurren Lagann and no multiplier) to 126 billion light years (with a 12-meter Gurren Lagann and the 10x multiplier). It is the third largest mech in anime to date, the other two being the Super Tengen Toppa Gurren Lagann, and the Super Granzeboma.

Power
Tengen Toppa Gurren Lagann is an extremely powerful mech, being materialized by Simon's Spiral power who integrated the whole Multiverse, Tengen Toppa Gurren Lagann has the mass of many higher dimensional multiverses (which each is infinite), with such an amount of latent power its able to create a whole Super Spiral Space within itself (which is a universe beyond the physical world). After absorbing the Infinity Big Bang Storm, its power shown to be increased drastically and able to directly match the unsuppressed Granzeboma.

Its 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 mech's abilities is immeasurable, as it gains an infinite amount of spiral power depending on the pilots' will to win. At points, the battle being so intense it was shown to open holes through various dimensions showing that the power of each was on a divine 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 nothingness, control space-time, quantum mechanics, transcend causality and destiny.

Tengen Toppa Gurren Lagann is an 11 dimensional mech and has all the abilities of previous Gurren Lagann forms. These include abilities such as reality warping, creating energy and matter out of nothing, bringing large entities into existence, teleporting, traversing between dimensions and universes, and manipulating space-time and probability.

Trivia

 * Tengen Toppa Gurren Lagann is one of two forms of Gurren Lagann that does not use a Giga Drill Break at any point in the show; Arc-Gurren Lagann being the other form. Arc-Gurren Lagann uses one against Cathedral Lazengann in the second movie, Super Galaxy Gurren Lagann uses one against a larger Ashtanga, and Tengen Toppa Gurren Lagann and Super Tengen Toppa Gurren Lagann use their respective Giga Drill Breaks against Antispiral's Super Granzeboma in the second movie.