Adam

No scene ever offers an unobstructed look at Adam's adult body. The available glimpses show it either sealed beneath Antarctic ice or burning as a featureless silhouette that observers call the Giant of Light. What can be made out is a humanoid colossus whose outline strongly recalls an Evangelion, a resemblance that makes sense given that the Evas are cloned from its tissue.

Footage of the Katsuragi Expedition digging the creature out shows no shoulder pylons, yet the Giant of Light clearly carries them. The implication is that researchers bolted the pylons on as restraints, anticipating the same measure later applied to the Evas. Second Impact undoes the giant entirely, shrinking Adam into a minute embryo, its four limbs already defined, resembling a tetrapod at the earliest stage of development.

Billions of years in the past, the First Ancestral Race fashions Adam and dispatches it inside the White Moon so that its offspring, the Angels, can populate the Earth. The plan collapses when a second transport, the Black Moon carrying Lilith, slams into the planet by accident. A world cannot host two Seeds, and because the crash destroys the Spear that should have shut Lilith down, Adam's own Spear of Longinus instead locks Adam away in suspended animation. Lilith's descendants inherit the Earth.

Ages later the Katsuragi Expedition uncovers the dormant giant in Antarctica. Fascinated by the S² Engine and its limitless output, the team runs the Contact Experiment, fusing a human donor's DNA into the Angel; the being later known as Kaworu Nagisa is strongly implied to be its product. Adam wakes, wipes out the surrounding life with an Anti A.T. Field, opens its Doors of Guf, and kills the researchers before losing control of its engine and detonating. Four enormous wings climb to the stratosphere as it self-destructs. Lilith-based life escapes annihilation, but the blast becomes the worldwide cataclysm remembered as Second Impact, and Adam reverts to an egg-like embryonic state while its soul separates from the flesh.

SEELE dredges both remnants from the dead sea left where Antarctica once was. The soul is salvaged into Tabris, while the embryo anchors Project E, the effort to grow Adam copies that become the Evangelions; only Unit-01 derives from Lilith instead. In 2015 Ryoji Kaji smuggles the embryo, frozen in dura-bakelite yet still alive, into Japan aboard a UN Pacific fleet and hands it to Gendo Ikari, telling him the Human Instrumentality Project hinges on it. Gendo later has the embryo grafted into his right palm, planning a forbidden joining of Adam with Lilith that would reunite him with Yui. Rei ruins the scheme: she tears off and absorbs his arm, takes Adam into herself, and rejects Gendo before merging with Lilith. Within the resulting gestalt, Adam surfaces briefly as a huge spectral Kaworu, suggesting Gendo salvaged the Angel's soul back into its body after Kaworu's death. The composite being perishes when Shinji refuses Instrumentality, and what finally becomes of Adam is never revealed.

Sadamoto's manga has Gendo swallow the embryo whole, gaining an eye in his palm and a defensive A.T. Field before Rei strips Adam from him all the same. In Neon Genesis Evangelion: the Iron Maiden 2nd, Adam traps Shinji inside a dream world until Kaworu's sacrifice apparently destroys them both.

Adam carries an S² Engine, a power source with effectively unlimited output, and can project translucent Wings of Light that swell and divide into four during Second Impact, reaching as high as the stratosphere. Its Anti A.T. Field annihilates nearby life, alters the surrounding atmosphere, and accompanies the opening of its Doors of Guf. As a Seed of Life it is meant to father the Angels, and its genetic material underpins nearly every Evangelion.