Margaret Thaler Singer (July 29, 1921 – November 23, 2003) was an American clinical psychologist and researcher with her colleague Lyman Wynne on family communication.

[5] After obtaining her PhD in clinical psychology, Singer worked at the University of Colorado's School of Medicine's department of psychiatry for eight years.

[5] In 1953, she started working at Walter Reed Army Medical Center, where she specialized in studying the returned prisoners of war who had been brainwashed by their captors into denouncing the United States and supporting North Korea and China.

Singer began to study brainwashing in the 1950s at Walter Reed in Washington, DC, where she interviewed United States soldiers who had been taken prisoner during the Korean War.

[4][9] Beginning in the late 1960s, she expanded her studies in the field of cults and published a number of articles on mind control ("psychological coercion") and similar areas.

Singer concluded that Bianchi had faked symptoms of multiple personality disorder, in order to escape responsibility for the murders of several women in Los Angeles.

[13] Melton has written that afterward, courts began to shift toward accepting the position held by the great majority of scholars studying new religious movements, moving away from the minority perspective of Singer and others sympathetic to her brainwashing claims.

[14] In the early 1980s, some American mental health professionals became well-known figures due to their involvement as expert witnesses in court cases against groups they considered to be cults.

"[15] Singer and her associate, sociologist Richard Ofshe, subsequently sued the APA, and a group of scholars and lawyers, in 1992 for "defamation, frauds, aiding and abetting and conspiracy,"[16] and lost in 1994.

[17] In a further ruling, James R. Lambden ordered Ofshe and Singer to pay 80,000 USD in attorneys' fees under California's SLAPP-suit law.

[24] Singer faced harassment, including death threats and dead animals placed on her doorstep, from groups that disagreed with her views on cults.

[9] According to the Los Angeles Times, other examples included cult operatives going through Singer's trash and mail, picketing her lectures, hacking into her computer, and releasing live rats in her house.