Masami Eiri 英利 政美 (Eiri Masami)
Eiri was a researcher at Tachibana General Laboratories and the main designer of Protocol 7, the next version of the Wired's underlying protocol. He believed that the flesh is only an engine and that humanity can evolve only by leaving it behind. In secret he wrote into the protocol code that would let the collective unconscious become conscious, with himself at its center. He appears late in the series as the voice and face of 'God' in the Wired, speaking to Lain with total confidence that he understands her better than she does. Konaka asked American fans in 2001 whether Eiri's dogma was totally insane; the Anime Expo panel answered that his ideas were not the problem so much as forcing them on others. In Layer 10 Konaka staged a scene where Eiri and Lain trade each other's thoughts and lines, borrowed from a technique used in therapy. Sho Hayami voices him.
More (spoilers)
Eiri was fired and found dead on the tracks, apparently a suicide, before the story begins. He tells Lain her family and friends were false and that he sent her into the world, and he claims the Knights as his believers until Lain exposes them. When Lain rejects him he tries to force himself into a body, a grotesque mass that Lain crushes. After the reset he is alive and ordinary, grumbling on his way to work at Tachibana.
Sources: en.wikipedia.org archived · ja.wikipedia.org archived · animenewsnetwork.com archived · konaka.com archived · lawmune.net · lain.wiki · lain.wiki