Leliel

Leliel is an "angel of the night" and a master of deception.
He appears (episode 16) as a floating, perfectly reflecting sphere. But when the Evangelions try to attack him, it seems as if he was intangible. He disappears and appears at another place, but cannot be hit be any weapon. Too late they discover, that not the sphere is their enemy, but the dark arae on the ground they thought to be a shadow (deception). In fact, the sphere is the 3-dimensional shadow of the (very thin) angel on the ground.
When Leliel starts to attack, he "sinks" everything his dark body (night) touches into his Dirac Sea. (Ahem...well, despite the fact that that only works for electrons .. which would strongly radiate in the process ... but come on, it's SciFi) Unit-01 sinks in as well, and Shinji is trapped in a white , boundless realm for quite some time.
When his air-supply finally is expleted, and his companions "above" planned to free him with all of their remaining N2-mines, Shinji (or more precisely Unit-01) rips Leliels "shadow" open from inside, and climbs out from the shining sphere, soaking the surrounding buildings in streams of angel-blood.