Thomas Roland Insel (born October 19, 1951) is an American neuroscientist, psychiatrist, entrepreneur, and author who led the National Institute of Mental Health (NIMH) from 2002 until November 2015.

[8] Insel is a Co-founder with Richard Klausner and Paul Dagum of a digital mental health company named "Mindstrong,"[9] a Bay-area startup.

He has also co-founded Humanest Care, NeuraWell Therapeutics, and MindSite News and is a member of the scientific advisory board for Compass Pathways, a company that is developing the psychedelic drug psilocybin to treat depression and other mental health disorders.

He hitch-hiked across Canada and through the West, married Deborah Silber soon after his 18th birthday, then traveled with her around the world, stopping to work at a TB clinic in Hong Kong and a mission hospital in Bihar, India.

These plans changed with exposure to two prominent Boston neuroscientists: Walle Nauta at MIT and Norman Geschwind at Harvard Medical School.

Following medical school, he trained in psychiatry at University California San Francisco (1976-1979) including in Jungian psychoanalysis and a first exposure to research with Irwin Feinberg.

A major focus was oxytocin, known to support lactation and parturition, but shown in rats to be important for the initiation of maternal care by actions on brain receptors.

Insel's return to become the ninth director of NIMH in 2002 was unexpected, as he had little connection to medical and pharmaceutical psychiatry since his OCD research which ended almost twenty years before.

At Verily, he founded and led the mental health team with a focus on digital phenotyping, using smartphone signals for measuring behavior and mood.

In 2019, he took a leave of absence from Mindstrong to assist newly elected California Governor Gavin Newsom on a reorganization of the state's behavioral healthcare system.

His work has been cited with features in the New York Times and The Atlantic and Wall Street Journal In addition to over 200 published scientific articles or chapters, books by Insel include: