Waldo Vieira is a Brazilian dentist and physician who first proposed the theories of projectiology and conscientiology, two closely related nascent sciences which posit that human consciousness is a non-physical phenomenon. That is, Vieira argues that consciousness has an existence independent from the body, basing his claims on various accounts of out-of-body experiences and other psychical phenomena. He has written dozens of books on vital energy, parapsychical and personal development, and out-of-body experiences, including accounts of personal experiences. He has been among the most prolific authors on the subject.

He was the founder and president of the International Institute of Projectiology and Conscienciology (IIPC), and is also a long standing member of the American Society for Psychical Research (ASPR) in New York, USA, the Society for Psychical Research (SPR) in London, England, the Brazilian Association of Parapsychology in Rio de Janeiro, Brazil, among others.

Vieira also assembled one of the largest libraries in the world on the subject of Consciousness, which includes works ranging from parapsychology to eastern mysticism. It's open to the public in CEAEC, Foz do Iguaçu, Brazil.