Harold Edward Puthoff (born June 20, 1936), often known as Hal Puthoff, is an American electrical engineer and parapsychologist known for his work in laser physics, remote viewing research, and theories on zero-point energy.

Puthoff was born in Chicago, Illinois. He received a BA and an MSc in electrical engineering from University of Florida. In 1967, Puthoff earned a Ph.D. in electrical engineering from Stanford University with a thesis, "The stimulated Raman effect and its application as a tunable laser". Puthoff then worked on tunable lasers and electron beam devices and co-authored (with R. Pantell) Fundamentals of Quantum Electronics (Wiley, 1969). Puthoff also published papers on polarizable vacuum (PV) and stochastic electrodynamics.

Puthoff took an interest in the Church of Scientology in the late 1960s and reached what was then the top OT VII level by 1971. Puthoff wrote up his "wins" for a Scientology publication, claiming to have achieved "remote viewing" abilities (called exteriorization in Scientology). In 1974, Puthoff also wrote a piece for Scientology's Celebrity magazine, stating that Scientology had given him "a feeling of absolute fearlessness". Puthoff severed all connection with Scientology in the late 1970s.

In the 1970s and 1980s, Puthoff directed a program at the Stanford Research Institute (SRI) to investigate paranormal abilities, collaborating with Russell Targ in a study of the purported psychic abilities of Uri Geller, Ingo Swann, Pat Price, Joseph McMoneagle and others, as part of what they called the Stargate Project. Both Geller and Swann convinced Puthoff and Targ that they possessed psychic powers, though Geller employed sleight of hand tricks.

Puthoff and Targ studied Uri Geller at SRI, declaring that Geller had psychic powers, though there were flaws with the controls in the experiments, and Geller used sleight of hand on many other occasions. According to Terence Hines:

Geller turned out to be nothing more than a magician using sleight of hand and considerable personal charm to fool his admirers. The tests at SRI turned out to have been run under conditions that can best be described as chaotic. Few limits were placed on Geller's behavior, and he was more or less in control of the procedures used to test him. Further, the results of the tests were incorrectly reported in Targ and Puthoff's Nature paper.

Psychologists David Marks and Richard Kammann attempted to replicate Puthoff and Targ's remote viewing experiments. In a series of thirty-five studies, they could not replicate the results. While investigating the procedure of the original experiments, Marks and Kammann discovered that the notes given to the judges in Puthoff and Targ's experiments contained clues as to which order they were carried out. Examples included referring to yesterday's two targets or the inclusion of the date of the session written at the top of the page. They concluded that these clues were the reason for the experiment's high hit rates. Terence Hines has written:

Examination of the few actual transcripts published by Targ and Puthoff show that just such clues were present. To find out if the unpublished transcripts contained cues, Marks and Kammann wrote to Targ and Puthoff requesting copies. It is almost unheard of for a scientist to refuse to provide his data for independent examination when asked, but Targ and Puthoff consistently refused to allow Marks and Kammann to see copies of the transcripts. Marks and Kammann were, however, able to obtain copies of the transcripts from the judge who used them. The transcripts were found to contain a wealth of cues.