Sylvan Muldoon (February 18, 1903 – October 15, 1969) was an American esotericist who promoted the concept of astral projection.

A 2012 Princeton University Press publication by Hugh Urban asserted that one of Muldoon's most popular books formed the basis for theories of the Church of Scientology founder L. Ron Hubbard which he claimed were his own.

In 1915, when he was 12 years old, Muldoon was said to have experienced his first OBE while at a Spiritualist camp in Clinton, Iowa with his mother that made him believe he had died.

[1] By 1927, Muldoon, as an earlier pioneer in the OBE field, was collaborating with the well-known British-born American investigator of psychic phenomena and author Hereward Carrington writing three books on OBE's, the most popular being their 1951 collaboration The Phenomena of Astral Projection.

[4] In 2012, Princeton University Press named Ohio State University professor Hugh Urban's[5] book on the Church of Scientology as one of their most outstanding academic titles for the year,[6] and wherein Urban asserted that L. Ron Hubbard had adopted many of Muldoon's theories as his own and stated that Hubbard's description of exteriorizing the body thetan is extremely similar if not identical to the descriptions of astral projection in occult literature popularized by Muldoon's widely read Phenomena of Astral Projection (1951) and Muldoon's description of the astral body as being connected to the physical body by a long thin, elastic cord that is virtually identical to the one described in Hubbard's "Excalibur" vision.